A speed performance measurement circuit that may perform speed performance measurement is provided between a first logic circuit and a second logic circuit. The speed performance measurement circuit includes a first flip flop that stores first data, a first delay circuit that delays the first data and generates second data, and a second flip flop that stores the second data. Furthermore, the speed performance measurement circuit includes a first comparator circuit that compares output of the first flip flop to output of the second flip flop, and a third flip flop that stores output data from the first comparator circuit in accordance with timing of the first clock signal. Data in a normal path is compared to data in a path delayed by a certain time to measure speed, and power voltage of a circuit is determined based on such comparison. Thus, change in speed with respect to power voltage in a critical path can be measured.