The invention is provided to obtain a stability evaluation test device and a stability evaluation test method for an electric storage device, which are capable of evaluating quantitatively the stability of the electric storage device. The stability evaluation test device is provided with: an operation/test control unit whereby the SOC of a test electric storage device being tested is set to a predetermined value, while the SOC of a standard electric storage device for comparison is set to a lower value than the SOC of the test electric storage device; a test data collection unit for measuring the temperature of the test electric storage device and the temperature of the standard electric storage device; and an evaluation and analysis unit for calculating the amounts of self-generated heat respectively for the test electric storage device and the standard electric storage device based on the temperatures of the electric storage devices measured at the test data collection unit, while evaluating the stability of the test electric storage device based on the ratio of the amounts of self-generated heat between the test electric storage device and the standard electric storage device.