An infrared detector includes a silicon substrate, an infrared reflecting film, a diaphragm including a bolometer thin film, disposed above the silicon substrate across a gap, and a signal line that electrically connects the bolometer thin film and the infrared reflecting film, such that the bolometer thin film and the infrared reflecting film constantly become equipotential with each other. In place of the signal line, a conductor independently provided from interconnects in the silicon substrate may be employed.