To repair quickly a constant temperature circulating equipment and to reduce the running cost of it by constituting it with a temperature regulating part, a circulation part and a control part separated into independent units in the constant temperature circulating equipment holding a object part at set temperature circulating liquid for circulation being adjusted to the set temperature.

A freezing unit 12 and a circulating water unit 13 are activated by the control of a control part unit 14 and circulating liquid cooled by an external heat exchanger to the set temperature is fed to a cooling tank unit 15 and the predetermined quantity of the liquid for circulation is stored inside the unit 15. The liquid for circulation is fed to the object part by the circulation pump of a circulating water unit 13 and cools the semiconductor wafers of the object part. The liquid for circulation returning from the object part flows from an inlet pipe through the external heat exchanger to the cooling tank unit 15 with the temperature of it being regulated to the set temperature again. In case the internal pressure of the cooling tank unit 15 is started to rise, the cooling means cools the inside of the cooling tank unit 15.