In an infrared imaging device, shutting means 40 is configured so that it can be opened/closed and so as to shut off an infrared radiation coming into an optical system 20 when it is closed. During an imaging operation, the shutting means 40 is opened, and the optical system 20 causes an infrared radiation from an object 70 to form an image on an infrared detector 10. The infrared detector 10 outputs a signal according to the amount of infrared light received by each pixel. Correction means 30 corrects sensitivity variations among pixels, the influence of the infrared radiation from the optical system 20, etc. During a calibration operation, the shutting means 40 is closed, and the correction means 30 determines a correction coefficient for correcting fluctuations in the amount of infrared radiation from the optical system 20 by using the output of the infrared detector 10 imaging the shutting means 40.