An image forming apparatus includes a storage portion, a cover member, a locking mechanism, an unlocking portion, and a contact portion. The storage portion conveys developer stored therein in a conveying direction parallel to a rotation axis by being rotated around the rotation axis parallel to a horizontal plane in a first direction. The cover member opens and closes an insertion hole portion, into which the storage portion is inserted, in a side face of the apparatus body. The locking mechanism imposes a restriction on a state change of the cover member from a closed state to an open state. The unlocking portion removes the restriction on the state change imposed by the locking mechanism as a lever portion swings in a second direction opposite the first direction. The contact portion includes a curved surface and rotates integrally with the storage portion to come into contact with the lever portion.