PURPOSE: To measure or monitor the temperature of a semiconductor chip as used actually by mounting a temperature monitor circuit in one semiconductor chip to which an integrated circuit is formed.

CONSTITUTION: A circuit 2 for monitoring a temperature is incorporated into an internal semiconductor chip in an IC1. Each terminal for the circuit 2 is lead out to external terminals for a package. When there are a plurality of the ICs, the ICs are connected in parallel by wires. When VEE is used as grounding potential, an input terminal I is supplied previously with approximately 0.7V and currents flowing through an output terminal O are detected, the output currents are changed by the temperature of a transistor T. The property is utilized, relationship between the output currents and the temperature is measured previously and correlative data are obtained beforehand, and the output currents are measured and the temperature of the semiconductor chip is grasped. When a plurality of ICs 1, 1', ..., 1" are connected in parallel, the temperature of the ICs as the highest operating temperature can be obtained.