A biological information detector is adapted to be attached to a users body. The biological information detector includes a light-emitting part, a reflecting part, a light-receiving part, a processing unit and a support part. The light-emitting part is configured to emit light toward the users body. The reflecting part is configured to be disposed in periphery of the light-emitting part and to reflect at least part of the light emitted by the light-emitting part toward the users body. The light-receiving part is configured to receive light reflected at the users body to produce a light reception signal. The processing unit is configured to process the light reception signal to produce biological information. The support part supports the light-emitting part. A thickness of the support part is within a range from 50 μm to 1000 μm.
