A semiconductor integrated circuit has first and second delay circuits that have n (n is an integer equal to or larger than 2) delay elements connected in series, respectively, and in which an identical input signal is inputted to delay elements at a first stage and output signals of delay elements at a kth (k is an integer satisfying a condition 1≦k≦n−1) stage are inputted to delay elements at a k+1th stage and a detection circuit that has n edge detecting units and a readout unit and in which a jth (j is an integer satisfying a condition 1≦j≦n) edge detecting unit is inputted with an output signal of a delay element at a jth stage of the first delay circuit and an output signal of a delay element at an n−j+1th stage of the second delay circuit, detects whether periods of rising or falling changes of the two signals overlap, and counts a number of times of the detection, and the readout unit reads out the counted number of times of the detection.