An apparatus and a method for detecting a phase delay of a resolver are provided. The apparatus includes a resolver configured to output a signal corresponding to a rotation angle of a motor, an excitation signal generator configured to generate an excitation signal using a square wave signal, and a controller configured to differentiate the signal to obtain a differential signal, detect a time when the differential signal meets a reference voltage as a peak time of the signal, and detect a phase delay time of the signal based on the peak time of the signal and an edge time of the square wave signal.