A developing device includes a developer carrier configured to rotate while carrying a magnetic developer on a surface of the developer carrier by a magnetic force, and a facing component that faces the developer carrier, is disposed at a position where the facing component frictionally slides against the developer moving along with rotation of the developer carrier, and is made of a material having the same polarity as the developer in terms of chargeability.

A development device includes a first sheet that is fixed to the cover, the first sheet being arranged to contact a magnetic brush, and a second sheet that is fixed to the cover, the second sheet being arranged to be superimposed on a first surface of the first sheet. With respect to the rotational direction of the developing rotation member, a free end of the first sheet is disposed on a downstream of a position where the regulating portion opposes the developing rotation member and on an upstream of the closest portion between the developing rotation member and the image bearing member. With respect to the rotational direction of the developing rotation member, a free end of the second sheet is disposed on the downstream of the position where the regulating portion opposes the developing rotation member and on an upstream of the free end of the first sheet.

A development device includes a development container having a first conveyance chamber and a second conveyance chamber above it, first and second stirring conveyance members that stir developer in the first and second conveyance chambers and convey it in the opposite directions, a developer carrying member that carries on its surface the developer in the second conveyance chamber, and a regulation blade. Feeding of the developer to the developer carrying member and collection of the developer from the developer carrying member are performed in the second conveyance chamber. A horizontal straight line L1 through the center of the rotation shaft of the second stirring conveyance member is above a horizontal straight line L2 through the center of the rotation shaft of the developer carrying member and the straight line L2 is above a horizontal straight line L3 through the center of the rotation shaft of the first stirring conveyance member.

A development device includes a developer container having a first conveyance chamber and a second conveyance chamber above it, a first stirring-conveyance member, a second stirring-conveyance member, a developer carrying member, and a regulation blade. The developer carrying member includes a magnetic member having a regulation pole, a main pole, a release pole, and an attracting pole. A release start position at which the magnetic force of the release pole becomes 5 [mT] or less is below a straight line L1 horizontally passing through the center of a rotation shaft of the second stirring-conveyance member and when the central angle of a developer releasing region where the magnetic force between the release pole and the attracting pole is 5 [mT] or less is represented by X [] and the peak magnetic force of the attracting pole is represented by Y [mT], Y2.1X32.7 is satisfied.

A developing device includes a second rotatable member and a guiding portion having an inclined surface. In a case where a normal component of magnetic flux density of the second rotatable member is Br, a tangential component of the magnetic flux density is B, an absolute value of a synthetic component of Br and B is |B|=(Br.sup.2+B.sup.2), and a distance from an arbitrary point to the inclined surface is d, a maximum position which is a position where |B|/d as an index obtained by dividing |B| by d becomes maximum is positioned on a side downstream, with respect to a rotational direction of the second rotatable member, of a closest position on the outer peripheral surface of the second rotatable member, which is a position where the outer peripheral surface of the second rotatable member is closest to the guiding portion.

A developing device includes a first rotatable member, a second rotatable member, a first feeding screw, a second feeding screw, and a guiding portion. In a case where a normal component of magnetic flux density of the second rotatable member is Br, a tangential component of the magnetic flux density is B, and an angle of a magnetic brush is arctan (Br/B), there is a portion where the angle of the magnetic brush is 45 or more in a range from an intersection point where a rectilinear line passing through an end portion of the guiding portion and a rotation center of the second rotatable member crosses an outer peripheral surface of the second rotatable member, to a closest point where the outer peripheral surface of the second rotatable member is closest to the guiding portion.