A belt unit includes a belt wound around a plurality of rollers to rotate endlessly, a contact member disposed along a surface of the belt, an opposing member disposed facing the contact member via the belt, a moving member including an action receiving portion, to swing and movably support the opposing member to contact and separate from the belt, and a moving assembly. The moving assembly includes an actuator to bias the action receiving portion in a first direction in which the opposing member contacts the belt and in a second direction opposite the first direction in which the opposing member separates from the belt, a drive mechanism to move the actuator in the first and the second directions, and an elastic member to transmit a moving force of the actuator to the action receiving portion when the actuator moves.