A signal component amount calculation unit calculates dispersion or standard deviation of multiple times of infrared detection signals detected by each detector element to be processed, and calculates the amount of a signal component dependent on infrared rays incident on the infrared detector included in the infrared detection signals, on the basis of the calculated dispersion or standard deviation. A fixed pattern noise calculation unit calculates the amount of a fixed pattern noise component on the basis of the infrared detection signals and the calculated amount of a signal component. A data update unit updates the fixed pattern noise data with the calculated amount of a fixed pattern noise component.