An infrared sensor element is provided that includes a pyroelectric element having a first main surface facing a first side in a thickness direction and a second main surface overlapping with the first main surface as viewed from the thickness direction and facing a second side in the thickness direction. The sensor element includes a first-side electrode on the first main surface; and a second-side electrode on the second main surface and overlapping with the first-side electrode as viewed from the thickness direction. As viewed from the thickness direction, the first-side electrode or the second-side electrode has a curved outer edge portion that is parabolic in shape.