An alternate current rectifier circuit which includes a first diode, a second diode, a first transistor, a second transistor, a third transistor, and a fourth transistor is power saving. The first diode is connected to the first transistor and the fourth transistor; the second diode is connected to the second transistor and the third transistor. During a positive half cycle of the alternate current, the first transistor and the fourth transistor are switched on and the alternate current flows through the first diode, the first transistor, and the fourth transistor; during a negative half cycle of the alternate current, the second transistor and the third transistor are switched on and the alternate current flows through the second diode, the second transistor, and the third transistor.