The present invention discloses an apparatus for slew rate enhancement of an operational amplifier, wherein an auxiliary control device and an auxiliary output device are added to the output stage of an operational amplifier. The auxiliary control device mirrors the current of the output stage and then compares the mirrored current with a reference current to generate an auxiliary push/pull control signal, which is used to control the auxiliary output device. When the output signal is different from the input signal, the auxiliary control device turns on the auxiliary output device to provide an auxiliary output current for the output terminal. When the output signal is equal to the input signal, the auxiliary output device is turned off.