Developing device and image forming apparatus

A developing device comprising:

• a housing that includes an accommodating portion that accommodates developer, a development opening portion that is formed continuously with the accommodating portion, a developing roller that is rotatably disposed at a side of the accommodating portion with respect to the opening portion, and a supply receiving portion having a receiving opening that receives supply developer that is supplied to the accommodating portion;
• an opening/closing member that is mounted on the supply receiving portion of the housing, the opening/closing member moving between a position where the receiving opening is uncovered and a position where the receiving opening is covered;
• a guiding portion that is provided at the supply receiving portion of the housing, the guiding portion guiding movement of the opening/closing member;
• and
• an elastic pushing member that pushes the opening/closing member towards the position where the receiving opening is covered,
• wherein the opening/closing member includes a body, a guide portion, and an extended protrusion, the body having a cutaway end portion that is formed by cutting away a corner located at one of left and right end portions, the left and right end portions corresponding to left and right sides when the opening/closing member moves between the position where the receiving opening is uncovered and the position where the receiving opening is covered, the guide portion being provided at the left and right end portions of the body except where the cutaway end portion exists, the guide portion being guided by contacting the guiding portion so as to surround the guiding portion from an outer side thereof, the extended protrusion being formed by causing at least a portion of an end portion of the body to extend and protrude in an opening direction when the opening/closing member moves to the position where the receiving opening is uncovered, the end portion corresponding to a leading side in the opening direction, and
• wherein the housing is provided with a sandwiching holding portion that holds at least a portion of the extended protrusion of the opening/closing member by sandwiching at least the portion of the extended protrusion by the sandwiching holding portion and the supply receiving portion.