A semiconductor device includes a first internal voltage driving unit configured to drive an internal voltage, a second internal voltage driving unit configured to drive the internal voltage in an operation period corresponding to an enable signal, a current amount detection unit configured to detect amount of current supplied by the first internal voltage driving unit, and a current amount comparison unit configured to compare the amount of detected current by the current amount detection unit with amount of a reference current, and determine whether or not to activate the enable signal in response to a comparison result.