Use status detecting mechanism and image-producing unit

A use status detecting mechanism includes a cover having an edge portion, in a portion of which a notch is formed, a moving member having a rod member, a spring portion, protrusions and grooves, and a shaft having a driving gear and ribs. In the unused state of a developing unit, the rod member is maintained to be exposed by the contact of the protrusions with the edge portion from the outside. When the developing unit is started to be used and rotation is transmitted to the driving gear, the moving member is rotated by the engagement of the ribs and the grooves, and the moving member is moved to the shaft side by the elastic force of the spring portion when the protrusions are opposed to the notches. Thus, the rod member is retreated from the exposed position.