To provide a slit plate for a steering angle sensor which can be manufactured with ease and high precision at low cost.

A plate material 33 comprising a circular insert-hole 37 where a steering shaft is inserted is formed of such material as allow transmission of light from a light-emitting element. A mask part 39 which shields light from the light-emitting element is selectively printed on the surface of plate material 33, so that plural light-transmission parts 41 are formed on concentric circles 40 of the insert-hole 37 of the plate material 33.