A receptacle (6) includes an optical fiber stub (7). A lens (5) includes an incident-side curved surface (9), an emission-side curved surface (10), and a barrel (11) provided between the incident-side curved surface (9) and the emission-side curved surface (10). A receptacle holder (8) holds the receptacle (6) so that the lens (5) and the optical fiber stub (7) are not in contact but separated from each other. When light out from the optical fiber stub (7) enters the lens (5) through the incident-side curved surface (9), the light is condensed inside the lens (5) and then spreads again, and the light out from the emission-side curved surface (10) is condensed onto a light-receiving surface of the light-receiving device (2).