System for controlling clutch

A system for controlling a clutch is provided with: a thrust member movable between a first position for disconnecting the clutch and a second position for connecting the clutch; a solenoid generating a magnetic flux in response to input of electric power; a movable element drivingly coupled with the thrust member and set into motion by the magnetic flux to drive the thrust member between the first position and the second position; an electric circuit configured to add alternating-current power to the electric power and apply the electric power with the alternating-current power to the solenoid; and a controller configured to detect a phase difference of an electric current relative to an electric voltage in the alternating-current power added to the electric power and compare the detected phase difference with a reference value to determine whether the thrust member is at the first position or at the second position.