A rotation angle estimation apparatus includes: a high-frequency voltage setting unit that sets high-frequency voltages; a circuit operating unit that operates an electric power conversion circuit to apply each of the high-frequency voltages to a corresponding one of winding groups of a rotating electric machine; and a rotation angle estimating unit that estimates a rotation angle of the rotating electric machine based on at least one of high-frequency currents that flow in the winding groups upon application of the high-frequency voltages to the winding groups. Moreover, the high-frequency voltage setting unit sets the high-frequency voltages based on the spatial phase difference between the winding groups so that in a fixed coordinate system of the rotating electric machine, the magnitude of a resultant vector of a plurality of high-frequency voltage vectors, which are respectively applied to the winding groups, becomes smaller than the magnitude of each of the high-frequency voltage vectors.