A biological information detector includes a light-emitting part, a reflecting part, a light-receiving part, a protecting part, and a processing part. The reflecting part has a curve shaped reflecting surface that is configured to reflect light emitted by the light-emitting part. The light-receiving part is configured to receive incident light that is emitted by the light-emitting part and reflected at a detection site of a user. The protecting part is configured to protect the light-emitting part, and the protecting part haw a contact surface adapted to contact with the detection site. The processing part is configured to process a light-receiving signal outputted from the light-receiving part. The light-emitting part has a light-emitting surface substantially in parallel to the contact surface, and a distance between the light-emitting surface and the contact surface is within a range of 0.4 mm to 0.9 mm.
