PURPOSE: To provide a freezing device which reduces the number of components, has all necessary control functions through a simple and low-cost freezing cycle, improves control efficiency and control precision, and improves assembly workability.

CONSTITUTION: A hot gas control means is formed such that, based on detecting signals from temperature sensors 41 and 42 located on the refrigerant inlet side and outlet side of a cooler 39, the opening of a PMV expansion valve 40 during normal freezing operation is controlled, and by means of a defrosting bypass circuit 36 to guide hot gas directly to a cooler after bypass of it through a condenser 32 and a detecting signal from a temperature detecting sensor on the outlet side, the opening of a PMV expansion valve is controlled to perform defrosting of a cooler. A case temperature sensing sensor 38 to sense the case temperature of a compressor 30 to control the opening of the PMV expansion valve, and return wet gas to the compressor and effect cooling during the generation of the abnormal high temperature of the compressor is provided.