A resolver is provided with a rotor plate fitted to a key groove in a rotating shaft and connected to the rotating shaft, and also with a resolver stator for detecting the rotational position of the rotor plate. The resolver stator is provided with a resolver cover for protecting a coil board of a stator core and fixed to the stator core. The coil board is provided with holes fitted to stator pins which are projections of the stator core, coil patterns each formed so as to center on each of the holes, and lead wires connected to the coil patterns formed on the coil board. The outer peripheral portion of the stator core is provided with long mounting holes for fixing the resolver to the housing of a rotating machine, such as an electric motor or a generator, and also with engaging holes engaging with claws of the resolver cover.