PURPOSE: To obtain a thin-film pyroelectric sensor which has a favorable characteristic and restrains the generation of a crack in the part of a pyroelectric-substance thin film by a method wherein a buffer film, composed of an insulator, having a characteristics as a coefficient of linear expansion which is intermediate between that of the pyroelectric-substance thin film and that of an insulating support film is interposed between the pyroelectric-substance thin film and the insulating support film.

CONSTITUTION: An insulating support film 8 is formed on one surface of a semiconductor substrate 6. After that, a lower electrode 9 and its extraction interconnection pattern 10 are applied to the film, and, in addition, a buffer film 12 is applied to the peripheral edge part of the lower electrode 9. The semiconductor substrate 6 on the lower side of the insulating support film 8 is etched to remove, and a removed part 7 is generated. The buffer film 12 is applied to cover a part corresponding to a contact region in which a pyroelectric-substance thin film 11 comes into contact with the insulating support film 8. The coefficient of linear expansion of a material as PLT for the buffer film 12 is smaller than that of PZT for the pyroelectric-substance thin film 11 and larger than that of (Si3N4+SiO2) for the insulating support film 8. As a result, the difference in a coefficient of linear expansion between the films which come into contact becomes small, and it is possible to prevent the generation of a crack due to the influence of a thermal expansion stress.