Developing device including exhaust passage and blocking member and image forming apparatus

A developing device comprising:

• a device housing configured to contain developer;
• a developer holding member configured to include a magnetic field generating device therein and to hold the developer;
• and
• a supply member configured to rotate so as to lift the developer from below on a developer lifting side in a rotational direction thereof toward the developer holding member to supply the developer,
• wherein the developing device comprises an exhaust passage that comprises an inlet, that is provided along an outer circumference of the developer holding member in the device housing, and that allows air in the device housing to be exhausted therethrough,
• wherein an opposite portion is defined on an opposite side to the developer lifting side in the rotational direction of the supply member,
• wherein the developing device comprises a blocking member that intersects a tangent connecting the opposite portion to the inlet of the exhaust passage so as to block entrance of the developer into the exhaust passage,
• wherein the blocking member comprises a distal end disposed at a position separated further from the magnetic field generating device than a tangent connecting the developer holding member to the supply member,
• wherein the device housing comprises an inner wall having an upper portion, and the inner wall is positioned on the opposite side to the developer lifting side in the rotational direction of the supply member, and
• wherein the blocking member is integrally formed with the inner wall in the upper portion of the inner wall.