To always control the inner temperature of a chamber to be within a target value without the occurrence of an overshooting of the inner temperature of the chamber.

This thermostatic chamber characterized by comprising a fan 17 for circulating air in an air jacket 5, heat exchangers 13, 15 for exchanging the heat of the circulated air, the first detection sensor 9 for detecting the inner component of the chamber 1, the second detection sensor 19 for detecting the inner temperature of the air jacket 5, and a controller 21 for switching on or off the heat exchanger 15 on the basis of detection signals from the first and second detection sensors 9, 19 so that the inner temperature of the chamber is controlled within a target value.