PURPOSE: To provide an inexpensive pyroelectric infrared thin film element which has high sensitivity and a high speed of response and a manufacturing method of the element.

CONSTITUTION: A pyroelectric infrared thin film element is formed by successively forming a Pt film 3 oriented in (100)-direction, a first pyroelectric thin film 4 precipitated on the film 3, a second pyroelectric thin film 5 which is deposited on the film 4 and has a rough surface to increase the infrared-ray absorptance, and a light receiving section 6 composed of an infrared-ray transmitting electrode on a substrate 2 and removing the part, which is larger than the section 6, of the substrate 2 immediately below the light receiving section 6. The Pt film 3 is used as a lower electrode.