To provide a position detector for accurately detecting the positions of moving members such as pointers by achieving thinning of the whole detector in a simple configuration.

The position detector includes a sheet-like first light transmission member 22 to a support plate 11, and a first light emitting element 20 and a first light receiving element 21 on a circuit board 19 opposed to the support plate 11 by sandwiching a gear train mechanism 6. Thus, when emitting the first light emitting element 20, light from the first light emitting element 20 is taken in from an incident end 22a being one end of the first light transmission member 22 to be guided to the other end, and the guided light is emitted toward a pointer wheel 9 of the gear train mechanism 6 from an emission end 22b being the other end of the first transmission member 22. When the pointer wheel 9 rotates and a first light transmission hole 15 of the pointer wheel 9 corresponds to the emission end 22b being the other end of the first light transmission member 22, light from the first light emitting element 20 through the first light transmission member 22 is received with the first receiving element 21.