A photosensor includes: a support; a thermoelectric conversion material section that is disposed on a first main surface of the support and that includes a plurality of first material layers each having an elongated shape, a plurality of second material layers each having electrical conductivity and an elongated shape, and an insulating film, the first material layers and the second material layers each being configured to convert thermal energy into electrical energy; a heat sink that is disposed on a second main surface of the support and along an outer edge of the support; a light-absorbing film that is disposed in a region surrounded by inner edges of the heat sink as viewed in a thickness direction of the support so as to form temperature differences on the first main surface of the support in longitudinal directions of the first material layers.