A solenoid valve 70 is disposed in a pipe line between an expansion valve 60 and an evaporator 80 for rear seats side. When the cooling operation is switched to the operation of utilizing only evaporator 50 for front seats side from the operation of utilizing evaporators 50 and 80 for front seats side and rear seats side, the solenoid valve 70 is closed by closing the operation switches Sc and Sf. The solenoid valve 70 can restrain an occurrence of water hammer phenomenon by stopping a refrigerant flow in air-liquid phase at the downstream of an expansion valve.