a developing container configured to contain a developer containing toner and a carrier;

a rotatable developing member configured to carry and feed the developer to a developing position;

a magnet provided non rotatably and stationarily inside said rotatable developing member and provided with a regulating pole; and

a regulating portion configured to regulate an amount of the developer carried on said rotatable developing member by a magnetic force of the regulating pole,

wherein with respect to a rotational direction of said rotatable developing member, a local minimum position, where a magnetic flux density of the regulating pole in a normal direction relative to an outer peripheral surface of said rotatable developing member is a local minimum value, is downstream of a first local maximum position where the magnetic flux density of the regulating pole in the normal direction relative to the outer peripheral surface of said rotatable developing member is a first local maximum value, and is upstream of a second local maximum position where the magnetic flux density of the regulating pole in the normal direction relative to the outer peripheral surface of said rotatable developing member is a second local maximum value,

wherein with respect to the rotational direction of said rotatable developing member, an angle between the first local maximum position and the second local maximum position is 20° or more and less than 50°,

wherein with respect to the rotational direction of said rotatable developing member, a closest position on the outer peripheral surface of said rotatable developing member where said rotatable developing member is closest to said regulating portion is downstream of the first local maximum position and is upstream of the second local maximum position, and

wherein with respect to the rotational direction of said rotatable developing member, an angle from the second local maximum position to a position, where the magnetic flux density of the regulating pole in the normal relative to the outer peripheral surface of said rotatable developing member is a half value of the second local maximum value on a side downstream of the second local maximum position, is smaller than an angle from a position where the magnetic flux density of the regulating pole in the normal direction relative to the outer peripheral surface of said rotatable developing member is a half value of the first local maximum value on a side upstream of the first local maximum position to the first local maximum position.