A volume control device and a method thereof are provided. The volume control device adapted to a mobile electronic device comprises a signal generating unit generating a plus pulse signal and a minus pulse signal according to user's rotation operation, a detection unit detecting a connecting state between the volume control device and an earphone to generate a detection signal, and a control unit selecting one of a first volume modulation mode and a second volume modulation mode according to the detection signal. Under the first volume modulation mode, the control unit generates a first control signal according to the plus pulse signal or the minus pulse signal. Under the second volume modulation mode, the control unit generates a second control signal according to the plus pulse signal or the minus pulse signal. The mobile electronic device controls volume according to the first or second control signal.