A highly-sensitive, pyroelectric infrared sensing method and apparatus that can detect infrared temperature with high sensitivity throughout the entire electromagnetic wave range including millimeter waves and radioactive rays. The supersensitive infrared sensor is an infrared sensor of a type that emits electrons from a surface of a ferroelectric body having no emitter. Therefore, a gate electrode is not required to be provided in the vicinity of an emitter. Accordingly, since electrons are emitted directly from a PZT thin film, which serves as a ferroelectric body, in proportion to a temperature variation caused by irradiation of an infrared ray, only provision of an anode is required. Further, designation of machining conditions of the surface of the ferroelectric body is unnecessary.