A field emitter type pyroelectric infrared sensor was newly proposed. The sensor wasconstructed using field emitter tips, a MOSFET (metal-oxide-semiconductor field effect transistor) and a pyroelectric material. At first, a dependency of the emission current on the infrared incident light intensity was simulated To simulate the emission current, a measurement of the voltage responsibility on the pyroelectric material was carried out. A principle of the new sensor was confirmed by using an equivalent circuit for the infrared sensor, which is composed of discrete devices that are gated cone-shaped field emitters (n-type Si), an n-ch MOSFET and a sheet PZT. From the experiment results, it was found that the proposed device was sensitive to an infrared light of longer wavelength over 10μm and the emission current was proportional to the incident infrared light intensity. The experimental data coincided with simulated ones.