A plugged honeycomb structure includes: a plurality of honeycomb segments, a bonding layer, and plugging portions to plug open ends of cells of the honeycomb segments. The honeycomb segment is configured so that the cells having at least two kinds of different shapes are disposed in a cross section orthogonal to an extension direction of the cells, the honeycomb segment has a center region configured by repeating units to maintain a repeated pattern including cell arrangement in which inflow cells surround an inflow cell, and a circumferential region located at the circumference of the center region, the circumferential region has open frontal area that is larger than open frontal area of the center region at the inflow end face of the honeycomb segment, the segment circumferential wall and the bonding layer have a special range of a thickness.

A plugged honeycomb structure, including: a plurality of honeycomb segments, a bonding layer and a circumferential wall disposed to surround circumference of a honeycomb segment bonded body where the plurality of honeycomb segments are bonded, wherein in the bonding layer, the bonding layer at a part that bonds the honeycomb segments disposed in contact with the circumferential wall is a circumferential bonding layer, and the bonding layer at a part that bonds the honeycomb segment including a center of gravity in a cross section orthogonal to the extending direction of cells of the honeycomb segment bonded body or at a position closest to the center of gravity and another honeycomb segment adjacent to the honeycomb segment is a center bonding layer, and a bonding strength A1 of the circumferential bonding layer is larger than a bonding strength A2 of the center bonding layer.

A honeycomb structure including prismatic columnar honeycomb segments and a bonding layer, wherein the bonding layer has rows in each of which bonding layer portions each disposed between two honeycomb segments arranged to face each other are arranged to extend from one point of a peripheral edge of a bonded body of the honeycomb segments to the other point thereof, in a cross section, the bonding layer of each of the-rows is disposed so that among the bonding layer portions arranged in one direction, an outermost circumference bonding layer portion and at least one of the other bonding layer portions are not superimposed on each other on an extension line of the one direction, and a ratio of shift of side surfaces of adjacent honeycomb segments to a length of one side of a side surface of honeycomb segments having the same cross-sectional shape is 10% or less.

A plugged honeycomb structure includes: a plurality of honeycomb segments, a bonding layer, and plugging portions to plug open ends of cells of the honeycomb segment. Each honeycomb segment is configured so that the cells having at least two types of different shapes have a predetermined repeated sequence pattern. A circumferential-wall partially surrounded cell in which a partition wall and a segment circumferential wall are disposed so as to surround the cell has an area of open end that has a specific ratio to an area of open end of a partition-wall entirely surrounded cell including the cross-sectional shape of the circumferential-wall partially surrounded cell. The repeated sequence pattern of the cells is kept at a boundary between two of the honeycomb segments bonded with the bonding layer at an inflow end face and an outflow end face.

The plugged honeycomb structure includes a plurality of honeycomb segments, a bonding layer, and plugging portions which plug open ends of cells of each honeycomb segment, and in the honeycomb segment, at least two types of cells having different sectional shapes are formed to constitute predetermined repeated arrangement patterns, and a ratio of a value R2s obtained by dividing an average sectional area S2.sub.in of inflow cells by an average sectional area S2.sub.out of outflow cells in a partial rim circumferential wall cell region is in a range of 1.7 times or more and 2.0 times or less to a value R1s obtained by dividing an average sectional area S1.sub.in of the inflow cells by an average sectional area S1.sub.out of the outflow cells in a whole rim partition wall cell region.

The plugged honeycomb structure includes a plurality of honeycomb segments, a bonding layer, and plugging portions which plug open ends of cells of each honeycomb segment, and in the honeycomb segment, at least two types of cells having different sectional shapes are formed to constitute predetermined repeated arrangement patterns, and in rim circumferential wall cells including rims of the cells surrounded with partition walls and segment circumferential walls, an inflow open area of each corner rim circumferential wall cell disposed in each corner portion of the honeycomb segment is 1.1 times or more as large as an average inflow open area of non-corner rim circumferential wall cells arranged in portions other than the corner portions, or an outflow open area of the corner rim circumferential wall cell is 1.1 times or more as large as an average outflow open area of the non-corner rim circumferential wall cells.

A honeycomb structure has a plurality of pillar honeycomb segments with a porous partition wall that defines a plurality of cells extending from an inflow end face as one end face to an outflow end face as another end face and becoming channels for a fluid and a bonding layer that bonds side surfaces of the plurality of honeycomb segments one another, the bonding layer contains a plurality of plate-shaped particles, the plate-shaped particles are laminated in a thickness direction X of the bonding layer at a cross section of the bonding layer cut off to the thickness direction of the bonding layer, the number of particles meets Expression: number of particles >10, and the number of particles and the number of particles meet a relationship of Expression: (number of particles /number of particles )>3.

A plugged honeycomb structure includes: a plurality of honeycomb segments, a bonding layer, and plugging portions to plug open ends of cells of the honeycomb segment. Each honeycomb segment is configured so that the cells having at least two types of different shapes have a predetermined repeated sequence pattern. A circumferential-wall partially surrounded cell in which a partition wall and a segment circumferential wall are disposed so as to surround the cell has an area of open end that has a specific ratio to an area of open end of a partition-wall entirely surrounded cell including the cross-sectional shape of the circumferential-wall partially surrounded cell. The repeated sequence pattern of the cells is kept at a boundary between two of the honeycomb segments bonded with the bonding layer at an inflow end face and an outflow end face.

A plugged honeycomb structure includes: a plurality of honeycomb segments, a bonding layer, and plugging portions to plug open ends of cells of the honeycomb segments. The honeycomb segment is configured so that the cells having at least two kinds of different shapes are disposed in a cross section orthogonal to an extension direction of the cells, the honeycomb segment has a center region configured by repeating units to maintain a repeated pattern including cell arrangement in which inflow cells surround an inflow cell, and a circumferential region located at the circumference of the center region, the circumferential region has open frontal area that is larger than open frontal area of the center region at the inflow end face of the honeycomb segment, the segment circumferential wall and the bonding layer have a special range of a thickness.

A plugged honeycomb structure includes: a plurality of honeycomb segments, a bonding layer, and a plugging portions to plug open ends of cells of each of the honeycomb segments. The honeycomb segment is configured so that the cells having at least two kinds of different shapes are disposed in a cross section orthogonal to an extension direction of the cells, the honeycomb segment has a center region and an circumferential region located in the circumference of the center region, the center region has a cell arrangement pattern such that inflow cells surround one outflow cell, in the inflow end face of the honeycomb segment, the circumferential region has an open frontal area that is smaller than an open frontal area of the center region, the segment circumferential wall of the honeycomb segment and the bonding layer have a special thickness.