A resolver includes an excitation signal generator which generates a sine wave and a cosine wave as an excitation signal, a rotor which receives the excitation signal, and a rotary transformer which detects an output signal of the rotor, the resolver being arranged to detect angle information of the rotor. The resolver further includes a controller which outputs angle information at a zero cross point of the output signal detected by the rotary transformer. The resolver can provide high detection accuracy and be low in cost.