The present invention provides a battery charger and a method for preventing an overshoot charging current during a mode transition. The battery charger includes a charging regulation circuit for outputting a charging current whose amount is regulated based on a regulation signal at a control terminal, a first current sensing unit for sensing a current level and outputting an error signal based on both the current level and a first reference signal, an operational amplifier for generating the regulation signal, and a reference voltage generator which includes an ADC for converting the error signal outputted by the current sensing unit to a digital signal, and a DAC for converting the digital signal to a reference voltage.