A tape-type magnetic recording medium, includes a substrate; and a magnetic layer provided on the substrate. The magnetic recording medium is configured such that (1) (w.sub.maxw.sub.min)/w.sub.min400 [ppm] where w.sub.max and w.sub.min are respectively maximum and minimum of average values of width of the magnetic recording medium measured under four environments whose temperature and relative humidity are (10 C., 10%), (10 C., 80%), (29 C., 80%), and (45 C., 10%), respectively, and the magnetic layer has a squareness ratio of 65% or more in the vertical direction, and (2) 4.4T.sub.B/(T.sub.AT.sub.B) where T.sub.A is an average thickness of the magnetic recording medium and T.sub.B is an average thickness of the substrate.

A magnetic tape in which a tape thickness of the magnetic tape is 5.2 m or less, and in an environment with a temperature of 32 C. and a relative humidity of 80%, a frictional force F.sub.45 on the surface of the magnetic layer with respect to an LTO8 head measured at a head tilt angle of 45 is 4 gf to 15 gf, and a standard deviation of a frictional force F on the surface of the magnetic layer with respect to the LTO8 head measured at each of head tilt angles of 0, 15, 30, and 45 is 10 gf or less.

There is provided a magnetic recording medium of which an average thickness t.sub.T is t.sub.T5.6 , a dimensional change amount w in a width direction with respect to a change in tension in a longitudinal direction is 660 ppm/Nw, a squareness ratio in a vertical direction is 65% or more, and a width deformation coefficient b during long-term storage in a case where a long-term storage width change amount Y is defined as Y=blog(t) is 0.06 mb0.06 .

A magnetic recording medium is provided and includes a magnetic layer, a non-magnetic layer, a base layer and a back layer, wherein an average thickness t.sub.T of the magnetic recording medium is t.sub.T5.3 m, a dimensional change amount w in a width direction with respect to a change in tension in a longitudinal direction is 700 ppm/Nw, a thickness of the non-magnetic layer is 2.0 m or less, a squareness ratio measured in a vertical direction of the magnetic recording medium is 65% or more, and the magnetic layer includes a magnetic powder.

A magnetic recording medium includes a layer structure including a magnetic layer, a non-magnetic layer, and a base layer in this order, in which an average thickness t.sub.T is t.sub.T5.5 m, a dimensional variation w in a width direction to tension change in a longitudinal direction is 660 ppm/Nw, and an average thickness t.sub.n of the non-magnetic layer is t.sub.n1.0 m.

The magnetic recording medium includes a non-magnetic support; and a magnetic layer including a ferromagnetic powder, in which the ferromagnetic powder is a ferromagnetic powder selected from the group consisting of a hexagonal strontium ferrite powder and an -iron oxide powder, the number of recesses having a depth which is or more of a minimum recording bit length existing on a surface of the magnetic layer is less than 10/10,000 m.sup.2, and a ratio d/t.sub.mag of a value d which is of the minimum recording bit length to a thickness t.sub.mag of the magnetic layer is 0.15 to 0.50.

The magnetic tape includes: a non-magnetic support; and a magnetic layer including ferromagnetic powder, in which the ferromagnetic powder is ferromagnetic powder selected from the group consisting of hexagonal strontium ferrite powder and -iron oxide powder, and an amount of an edge weave of a tape edge on at least one side of the magnetic tape is 1.5 m or less.

In a magnetic recording medium, an average thickness t.sub.T is t.sub.T5.5 m, a dimensional variation w in a width direction to tension change in a longitudinal direction is 650 ppm/Nw, and a rate of shrinkage in the longitudinal direction is 0.08% or less.

The magnetic tape includes: a non-magnetic support; a magnetic layer that includes ferromagnetic powder on one surface side of the non-magnetic support; and a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support, in which the ferromagnetic powder is ferromagnetic powder selected from the group consisting of hexagonal strontium ferrite powder and -iron oxide powder, and the number of protrusions having a height of 50 nm or more and less than 75 nm on a surface of the back coating layer is 700 pieces/6400 m.sup.2 or less.

The magnetic tape includes a non-magnetic support, a magnetic layer that includes ferromagnetic powder having an average particle volume of 2,500 nm.sup.3 or less on one surface side of the non-magnetic support, and a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support, in which the ferromagnetic powder is ferromagnetic powder selected from the group consisting of hexagonal ferrite powder and -iron oxide powder, and a ratio (PSD.sub.5 m-PSDmag/PSD.sub.10 m-PSDbc) of the magnetic layer and the back coating layer is in a range of 0.0050 to 0.20. A magnetic tape cartridge and a magnetic recording and reproducing apparatus include the magnetic tape.