PURPOSE: To reduce the number of mask matching steps by forming a guard ring by a Schottky junction instead of a guard ring region formed by an N-type region.

CONSTITUTION: Infrared rays incident into a platinum silicide 1 generate electron and hole pairs, and holes having energy which exceeds the height of a Schottky junction barrier are implanted to a substrate. Electrons stored at a metal side electrode are read out as a signal electrode, and a guard ring 2 is formed of platinum silicide similarly to a detector. A depletion layer 4 depends upon a substrate density and a voltage applied to the Schottky junction in the Schot tky junction, but becomes several μm to 10μm or larger. The concentration of an electric field by the junction can be prevented by sufficiently superposing the elongation of the depletion layer from the detector and the elongation of the depletion layer from the junction provided as the guard ring. Thus, the variation in the detecting sensitivity due to the changes of the superposed por tion of the detector and the ring is avoided to obtain an accurate high infrared ray detector.