A switch circuit is provided. The switch circuit includes a P-type transistor switch and a first P-type control transistor. The P-type transistor switch includes a first control end, a first output end, and a first input end. The first input end receives a first input signal whose logic level is one. The first P-type control transistor is coupled to the first input end and the first control end. The first P-type control transistor includes a second control end. The second control end receives a second input signal whose logic level is zero to turn on the first P-type control transistor. When the first P-type control transistor is turned on, the first input signal is transmitted to the first control end of the P-type transistor switch to turn off the P-type transistor switch.