A thermal detector includes a substrate; a support member supported on the substrate interposed by a cavity; a heat-detecting element formed on the support member and having a pyroelectric material layer disposed between a lower electrode and an upper electrode; a light-absorbing layer formed on the heat-detecting element; and a thermal transfer member including a connecting portion connected to the heat-detecting element and a thermal collecting portion disposed inside the light-absorbing layer and having a surface area larger than that of the connecting portion in plan view, the thermal collecting portion being optically transmissive at least with respect to light of a prescribed wavelength. The lower electrode has an extending portion extending around the pyroelectric material layer in plan view, and the extending portion has light-reflecting properties by which at least a part of the light transmitted through the thermal collecting portion of the thermal transfer member is reflected.