Abstract: A method successively test information processing devices, that include a main storage, a CPU, an external storage, etc., in a plurality of test steps in accordance with test programs along a test line composed of baths with different temperatures/humidities. A table and a pointer corresponding to the table are stored in an external storage and a non-volatile memory, respectively. A test program, test items and a test procedure are previously described for each test step in the table. The test object is shifted to a certain bath on the test line, and a prescribed test for the test object is performed at the timing of turning-on of the driving power therefor in accordance with the test procedure described in the procedure table corresponding to the pointer. The value of the pointer is updated each time the power is turned on.