To provide a rotation detecting apparatus miniaturized, improving the degree of freedom for disposing a rotating body, and accurately detecting a rotating state.

The rotation detecting apparatus 100 is disposed adjacent to an outer circumference of the rotating body 1, measures a change in a bias magnetic field due to a rotation of the rotating body 1, detects the rotating state of the rotating body 1. The rotation detecting apparatus 100 includes: a multilayer wiring board 50 disposed adjacent to the outer circumference of the rotating body 1; and multilayer wired coils La, Lb embedded in the multilayer wiring board 50 and formed at an end adjacent to the outer circumference of the rotating body 1.