A semiconductor device includes a voltage adjust circuit suitable for generating an adjusting voltage according to a counting signal; an oscillating circuit operable by an oscillating control signal, and suitable for outputting an operational clock signal whose frequency is controlled by the adjusting voltage; a pumping circuit suitable for generating an internal voltage by pumping a source voltage according to the operational clock signal; and a counting circuit suitable for generating the counting signal by counting the operational clock signal according to the oscillating control signal.