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 magnetic 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 magnetic 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 magnetic 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 magnetic 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 magnetic 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 position where the magnetic flux density of the regulating magnetic pole in a tangential direction relative to the outer peripheral surface of said rotatable developing member is zero is between the first local maximum position and the second local maximum position,

wherein with respect to the rotational direction of said rotatable developing member, an opposing position where said regulating portion is opposed to the outer peripheral surface of said rotatable developing member is between the first local maximum position and the position where the magnetic flux density of the regulating magnetic pole in the tangential direction relative to the outer peripheral surface of said rotatable developing member is zero, and

wherein with respect to the rotational direction of said rotatable developing member, the position where the magnetic flux density of the regulating magnetic pole in the tangential direction relative to the outer peripheral surface of said rotatable developing member is zero is within a range of ±2° of a midpoint between the first local maximum position and the second local maximum position or is downstream of the range.