A first thermosensitive element including a temperature detecting unit that outputs a voltage corresponding to a temperature to which the unit rises from ambient temperature (temperature of surrounding environment) due to incident infrared, and a second thermosensitive element including a temperature detecting unit that outputs a voltage based on ambient temperature are formed above/on a silicon substrate. The temperature detecting unit of the first thermosensitive element is thermally insulated from the silicon substrate by a clearance (space). The temperature detecting unit of the second thermosensitive element is formed on a first sacrifice layer made of deposited diamond like carbon, and thermally connected to the silicon substrate by the first sacrifice layer. The infrared sensor detects an amount of incident infrared based on the difference between output voltages of the first and second thermosensitive elements.