In the semiconductor integrated circuit device, a first P+ type buried layer formed as an anode region and an N+ type diffused region formed in a cathode region are spaced from each other in the direction of the depth. This makes it possible to provide a semiconductor integrated circuit device in which a large depletion layer forming region can be provided in an N type region at a PN junction formed by first and second epitaxial layers and when a reverse bias voltage is applied to a diode element and in which a withstand voltage can be maintained by a depletion layer thus formed to prevent breakdown of elements in the device attributable to a breakdown current.