PURPOSE: To simultaneously measure the generating position and value of a leak current in a semiconductor integrated circuit by providing a semiconductor device for monitoring leak currents which directly measures a leak current in the vicinity of the semiconductor integrated circuit.

CONSTITUTION: A semiconductor device 6 for monitoring leak currents which directly measures a leak current is provided in the vicinity of a semiconductor integrated circuit 5. The light 7a emitted from the circuit 5 when the circuit 5 is operated is collected and the generating position of a leak current in the circuit 5 is decided by performing picture processing on the emitted intensity of the light 7a. At the same time, the value of the leak current at the leak current generating position in the circuit 5 is decided from the leak current flowing to the semiconductor device 6 for monitoring leak currents by comparing the light emitting intensity of the circuit 5 with that of the device 6. Therefore, the generating position and value of the leak current can simultaneously be measured.