An infrared sensor element according to the present invention includes a substrate, and a lower electrode layer, a pyroelectric layer, and an upper electrode layer sequentially formed on the substrate. The substrate has a linear thermal expansion coefficient higher than that of the pyroelectric layer, and the pyroelectric layer includes a polycrystalline body having an in-plane stress in a compressive direction. Thus, the infrared sensor element realizes the pyroelectric layer having a high orientation in a polarization axis direction, an excellent pyroelectric property.