A living body detection device (1) includes: an image acquisition unit (171), a determination unit (173) and a detection unit (174). The image acquisition unit (171) acquires a first image in which a subject irradiated by light in a first wavelength range is imaged, and a second image in which the subject irradiated by light in a second wavelength range is imaged, the second wavelength range being different from the first wavelength range. The determination unit (173) determines whether a relation expressed by luminance of the subject imaged in the first image and luminance of the subject imaged in the second image is a relation exhibited by a living body. The detection unit (174) detects that the subject is a living body in a case where the determination unit (173) has determined that it is the relation exhibited by the living body.