A biological-information detection device includes a video input section accepting video signals including three wavelength components in an infrared region of reflected light from an object, a wavelength detecting section acquiring a wavelength and an intensity of the reflected light from the video signals, a face feature amount detecting section detecting a plurality of feature points of a face based on the video signals, a measurement target area identifying section identifying a measurement target area on a basis of the plurality of feature points of the face detected, a wavelength fluctuation detecting section detecting a difference between a wavelength of reflected light from the measurement target area at a certain point in time and a wavelength of reflected light at a point in time preceding the certain point in time, and a pulse wave detecting section detecting a change in the detected difference according to the point in time.