A biological information detector includes a first sensor unit for detecting composite information including biological information of a test subject and first noise information originating in external light, having a first light-emitting part for emitting toward there, a first light-receiving part for receiving it including the biological information, reflected there, and the light including the first noise information obtained from the external light, transmitted through there, and a first reflecting and leading part for reflecting the light including the biological and the first noise information, leading it to the first light-receiving part, and a second sensor unit for detecting second noise information originating in the external light, having a second light-receiving part for receiving the light including the second noise information, obtained from the external light and transmitted through there, and a second reflecting, leading part for reflecting the external light and leading it to the second light-receiving part.
