An integrated digital circuit includes an oscillation circuit comprising basic gate circuits having the number of stages proportional to the number of gates existing in the critical path of a synchronized circuit network and capable of controlling an oscillating frequency by at least one control signal line. A synchronized circuit network constructed with basic gate circuits capable of controlling the delay time by at least one control signal line operates synchronously by an oscillation signal transfer line. A control circuit controls the oscillation circuit and the synchronized circuit network using the control signal line so that the frequency of signal input from an externally input signal line is equalized with the frequency of signal from the oscillation circuit. Thus, the synchronized circuit network can be always operated at the frequency obtained from the oscillation signal transfer line even though the delay time of the basic gate circuit varied by variations of the device characteristics and the like.