In a light converging type light guide unit for guiding light emitted from a light source to a light-receiving member having a reflection face extending from a light emission point to at least a place in the neighborhood of a light reception point of the light-receiving member, the reflection face has first and second focal points at which the light emission and reception points are disposed, respectively, and comprises an elliptical reflection face at the side of the light reception point, and a curved surface reflection face that is provided at the side of the light emission point, reflects light of the light source therefrom to the elliptical reflection face and obtains light that travels to the light reception point and is incident to the light reception point at a predetermined incidence angle or less by reflection from the elliptical reflection face.
