A clutch (10) is a fail-safe mechanism for a steer-by-wire system (100) which, when a defective condition occurs in the steer-by-wire system (100), places the clutch (10) in the engaged state and makes it possible to steer directly by a steering wheel (2) instead of by the steer-by-wire system (100). The clutch (10) is composed of a mechanical clutch section (11, 12, 13, 14), and a solenoid coil (17) for controlling the mechanical clutch section, and is a reverse actuation type clutch such that when the solenoid coil (17) is in the energized state, the mechanical clutch section is in the disengaged state, while when the solenoid coil (17) is in the de-energized state, the mechanical clutch section is in the engaged state.