A phase selector including a plurality of buffers, a multiplexer, a first inverter, and a selecting circuit is provided. Each of the buffers provides a clock signal, and the clock signals have different phases. The multiplexer selectively outputs one of the clock signals as a switch signal according to a first control signal, wherein the first control signal is first portion of bits of a selecting signal. The input terminal of the first inverter receives a second control signal, wherein the second control signal is second portion of bits of the selecting signal, and the output terminal of the first inverter outputs an inverted signal. The selecting circuit transmits the second control signal of the selecting signal or the inverted signal to the output terminal of the phase selector according to the logic state of the switch signal.