A supersonic wave beam producing device projects a supersonic wave beam 5 on a semiconductor integrated circuit chip 2 while a voltage is supplied to a semiconductor integrated circuit in the chip from a constant voltage source 1. A current detecting device 7 detects a change of a current in the circuit while the chip is supplied with the supersonic wave beam. In this event, the constant voltage source may be omitted. A supersonic wave beam producing device may project a supersonic wave beam 5 on a semiconductor integrated circuit chip 2 while a current is supplied to a semiconductor integrated circuit. In this event, a voltage detecting device detects a change of a voltage between two ones of terminals of the circuit.