A voltage regulator is provided. The voltage regulator includes an output terminal, a transistor, a primary driving circuit, and a secondary driving circuit. The output terminal is adapted to output an output voltage. The primary driving circuit is coupled to a control terminal of the transistor. The secondary driving circuit is coupled between the control terminal of the transistor and a predetermined voltage terminal. When the voltage regulator operates in a start-up mode, the transistor is driven by the primary driving circuit and the secondary driving circuit, and the control terminal of the transistor and the predetermined voltage terminal are electrically coupled by the secondary driving circuit. When the voltage regulator operates in a normal mode, the transistor is driven by the primary driving circuit, and an electrical coupling between the control terminal of the transistor and the predetermined voltage terminal is disconnected by the secondary driving circuit.