A state detection mechanism includes a movable member, a spring member, a fringesection, and a stopper member. The spring member displaces the movable member arranged at the first predetermined position to a second predetermined position by applying restoration force in a D direction to the movable member. The fringe section restricts the displacement by abutting to a protrusion member formed on the movable member arranged at the first predetermined position. The stopper member restricts rotation of the movable member, which rotates around an axis that extends in a D direction, by abutting to the protrusion member formed on the movable member arranged at the first predetermined position. When torque is transmitted to the movable member from a shaft, the movable member rotates wound an axis that extends in the D direction, and the protrusion member and the stopper member abut to each other.