PROBLEM TO BE SOLVED: To provide a device capable of noninvasively, easily and accurately measuring a body temperature of a small animal for an experiment, and to provide a method for measuring the body temperature of the small animal for an experiment using the device.SOLUTION: The invention relates to use of a body temperature measuring system for a small animal for an experiment includes a thermostat bath capable of housing more than one animal for an experiment and a thermocamera, wherein the thermostat bath has at least a temperature and humidity control unit and a ventilation unit.