A slave cylinder includes a first input port provided to a first slave hydraulic chamber and which is connected to a master cylinder and is selectively cut off from the master cylinder by a first shut-off valve; a second input port provided to a second slave hydraulic chamber and which is connected to the master cylinder and is selectively cut off from the master cylinder by a second shut-off valve; a first atmosphere port formed in a first back chamber disposed in rear of the first slave hydraulic chamber and which moves together with a first piston; a second atmosphere port formed in a second back chamber disposed in front of the first slave hydraulic chamber and which moves together with a second piston; and a restricting means to restrict the second piston. The second atmosphere port is disposed in the vicinity of the restricting means.