An apparatus for regulating output voltages is used to regulate and output DC voltages, and can output a plurality of DC voltages through a simple structure. The apparatus for regulating output voltages can handle the current mode, and has the function of overcharge protection. The apparatus for regulating output voltages comprises a voltage conversion and comparison module, an analog to digital conversion module, an accumulation module, a pulse generator, a timing generator, a switch module, and an overcharge protection module. The apparatus for regulating output voltages can regulate a plurality of output voltages to provide stable DC power sources required by electronic devices.