PURPOSE: To make an oscillating frequency of the ring oscillator circuit stable against a change in ambient temperature by allowing a temperature compensation means to control an output current from a constant current supply means in response to the ambient temperature so as to compensate a change in the oscillating frequency.

CONSTITUTION: Resistors R1, R2 connected in series are provided between a constant voltage node N1 and a ground potential point VSS in the ring oscillator circuit 7b. A poly silicon resistor having a negative temperature coefficient is employed for the resistor R2. The resistor R1 has a positive temperature coefficient and further the oscillating frequency from inverters 81-87 connected in cascade in a ring has a negative temperature coefficient and they act like the poly silicon resistor R2 having a negative temperature coefficient. Thus, the oscillating frequency is compensated against a change in ambient temperature, and then a reference clock signal generating circuit having the oscillating frequency not affected by a change in the ambient temperature is formed in a semiconductor substrate.