An apparatus for controlling optimization of a charging amount of a battery for a vehicle charged with external power includes: a map storage, a position detector, and a controller to control the map storage and the position detector. The controller acquires a current position of the vehicle when a driver's desired charging setting value is input, acquires altitude information of topography corresponding to a driving path, calculates a gain charging amount in an uphill or downhill section on the driving path based on the altitude information, calculates an optimum charging setting value based on the driver's desired charging setting value and the gain charging amount, calculates a final target charging amount based on the optimum charging setting value and a current residual charging amount, and performs optimum charging of the battery.