To provide a cooling apparatus provided with a Stirling refrigerating machine capable of defrosting and treatment of drain in defrosting time.

The cooling apparatus includes a free-piston type Stirling refrigerating machine 13, a low-temperature side machine room 15 comprising a cooler 14 connected to the refrigerating machine 13, a high-temperature side machine room 17 comprising a radiator 16 connected to the refrigerating machine 13, and a cooling chamber 18 for cooling an object to be cooled. As a defrosting means for the cooler 14, there are provided a means for defrosting by a heater 112 provided in the vicinity of the cooler 14, and a means for defrosting by heating the cooler 14 by controlling so that the phase difference in the periodic reciprocating motion of a piston and a displacer of the refrigerating machine 13 becomes substantially zero.