A clock diagnosis circuit includes: a delay circuit to delay the clock by a prescribed time which is not more than the clock pulse width; an integral multiplication delay circuit to delay a delayed clock outputted from the delay circuit by a prescribed number of cycles; a first exclusive OR circuit to encode the clock using the delayed clock; a second exclusive OR circuit to decode an output of the first exclusive OR circuit using an output of the integral multiplication delay circuit; and a comparison circuit to compare the clock with an output of the second exclusive OR circuit to thereby detect a malfunction of the clock.
