PROBLEM TO BE SOLVED: To provide a biological body sensor capable of accurately detecting a weak light component in the biological body sensor comprising light emitting elements and a light receiving element, and further to provide a biological body information detector.SOLUTION: A biological body sensor is constituted so as to comprise: a substrate 22 having light transmissive properties light-emitting elements 24 being provided at a mounting surface side of the substrate 22 and emitting light and a light receiving element 26 being provided at a non-mounting surface side of the substrate 22, receiving reflection light from a biological body out of the light emitted from the light-emitting elements 24 and outputting a signal corresponding to reception of the reflection light. More specifically, the light receiving element 26 is provided at the non-mounting surface side opposite to the mounting surface side where the light-emitting elements 24 are provided with respect to the substrate 22 and is positioned at recesses with a distance from a light emission surface equal to a thickness of the substrate 22 or more.
