A force for adjusting a relative position of a regulating blade relative to a development rotary member supported by a development frame member is applied to the regulating blade so that a gap between the development rotary member and the regulating blade when attached to an attachment portion falls within a predetermined range in a rotational axis direction of the development rotary member in a state that the regulating blade is separated from the attachment portion with an adhesive applied. The regulating blade is attached, with the adhesive, to the attachment portion with the adhesive applied so that the gap between the development rotary member and the regulating blade with the force applied falls within the predetermined range.