A voltage generator capable of preventing latch-up is disclosed. The voltage generator includes a positive charge pump unit, a negative charge pump unit, a second stage charge pump unit, and a control unit. The positive charge pump unit is utilized for generating a positive charge pump voltage according to a first enable signal. The negative charge pump is utilized for generating a negative charge pump voltage according to a second enable signal. The second stage charge pump unit is utilized for generating a gate-on voltage and a gate-off voltage according to a third enable signal and a fourth enable signal. The control unit is utilized for generating the first enable signal, the second enable signal, the third enable signal, and the fourth enable signal and make the second stage charge pump unit generate the gate-on voltage (or the gate-off voltage) in a successively-increasing (or decreasing) manner.