Disclosed is a charging apparatus mounted in a vehicle. The charging apparatus includes at least two power modules parallel to each other to convert input power applied from an outside into a chargingpower for charging a high-voltage battery, at least two slave controllers that outputs information about whether each of the power modules enters a constant-voltage charging mode, based on the charging power output from the power modules, and a master controller that determines whether the at least two power modules enter the constant-voltage charging mode by utilizing the information, which is received from the slave controllers, about whether each of the power modules enters the constant-voltage charging mode, wherein the master controller controls such that one of the power modules is operated when the power modules enter the constant-voltage charging mode.