An image forming apparatus includes a casing, an image forming unit movable between an accommodated position and a shifted position, an actuator, an urging member, a cam, and a contact portion. The actuator includes a pivot shaft and a protrusion protruding therefrom. The protrusion at a standby position crosses a conveyance path and is contactable with a sheet conveyed along the conveyance path. When the image forming unit is at the accommodated position, the contact portion and the cam contact each other and maintain the protrusion at the standby position against an urging force of the urging member. As the image forming unit moves from the accommodated position to the shifted position, the contact portion and the cam move away from each other such that the protrusion pivots from the standby position, by the urging force, to a retracted position at which the protrusion is retracted from the conveyance path.