A biological light measurement device has one or more light emission means arranged on a surface of a subject, one or more light detection means arranged on the surface of the subject, a holding unit for holding the light emission means and the light detection means, a mounting jig for mounting the holding unit on the subject, and means for changing an SD distance defined by a distance between the light emission means and the light detection means. The holding unit holds the light emission means and the light detection means so that two or more types of the SD distance are configured.
