A biological information detector includes a light-emitting part subjected to emit a first light directed at a detection site of a test subject and a second light directed in a direction other than a direction of the detection site, a first reflecting part subjected to reflect the second light and directing the second light towards the detection site, a light-receiving part subjected to receive light having biological information, where the light produced by the first light and the second light is reflected at the detection site, and a second reflecting part subjected to reflect the light having biological information from the detection site and directing the light having biological information towards the light-receiving part.