To provide a sensor device capable of preventing reduction in detection distance of an optical sensor and providing superior detection accuracy, and a toilet seat device having the same.

A sensor device 5 includes a housing 6, a window plate 9, a seating detection sensor 7, and a human body detection sensor 8. The housing 6 has a front plate portion 10 which is placed flush with an exterior surface of a toilet seat box 2, a window opening 11 provided on the front plate portion 10, and a sensor holder portion 12 integrally provided on the rear side of the front plate portion 10. The window plate 9 has light transmissive plates 13 and 14 made of an infrared transmissive material, and an optical shield section 15 provided between the transmissive plates 13 and 14.