An integrated circuit includes a clock generator and a synchronous clock circuit unit. The clock generator generates a first clock signal, a second clock signal, and a third clock signal, which are synchronized with one another and are provided with mutually different frequencies. The synchronous clock circuit unit includes synchronous clock circuits to which the first clock signal, the second clock signal, and the third clock signal are inputted, respectively. The synchronous clock circuits are scanned by use of the first clock signal, the second clock signal, and the third clock signal.