PURPOSE: To provide a pyroelectric infrared ray sensor of good responsiveness and also a small multi-element type pyroelectric infrared ray sensor that ignores crosstalk effect.

CONSTITUTION: On a substrate 3 consisting of an insulation material, semiconductor material or composite material, or inside of it, a removable part is formed, and at the upper part of it, a supporting layer 10 is formed, and by removable- formation of said removable part, a supporting layer having a void 9 at its bottom is formed, and then, on the top of it, an electrode 8, a thin layer, consisting of a pyroelectric material, and an electrode are farmed, thus a pyroelectric infrared ray sensor is constituted. With this, conversion efficiency and responsiveness of the pyroelectric infrared ray sensor is improved, and thermal separation of respective elements becomes possible.