A developing unit is to be attachable to and detachable from an image forming device main body. The developing unit is provided with a developer case, a developing roller coupled with the developer case, and a movement member coupled with the developer case. The movement member is capable of moving between a housing position where the movement member is substantially housed inside the developer case and a protruding position where the movement member protrudes beyond the developer case. The movement member is positioned at the protruding position and pushed by the image forming device main body in a predetermined direction while the developing unit is being attached to the image forming device main body.