A rotational position sensor includes a rotor substrate and a stator substrate placed to face each other to detect rotational displacement of the rotor substrate. The rotor substrate is formed with an excitation coil in a meandering pattern on an outer circumferential side and a rotor-side rotary transformer on an inner circumferential side. The stator substrate is formed with four detection coils in a meandering pattern on an outer circumferential side and a stator-side rotary transformer on an inner circumferential side. The four detection coils are arranged in a circumferential direction without overlapping each other. The detection coils are displaced from each other by 360°/8. The rotational position sensor includes a high frequency excitation circuit for applying a high frequency signal to the excitation coil through the rotor-side rotary transformer and the rotor-side rotary transformer to excite the excitation coil.