A charging device capable of appropriately grasping the charged state of a battery pack using data stored in a memory of the battery pack even when the battery pack becomes commercial as a new product. A charging device determines charged state data indicative of a charged state of a battery pack mounted thereon based on a charging current supplied and/or a charging voltage applied to the battery pack. A charge control microcomputer reads charging characteristics data from a memory of the battery pack, and generates a data table associating at least one of the charging current supplied and the charging voltage applied to the battery pack and the charged state data with each other, based on the charging characteristics data read out. The microcomputer determines charged state data indicative of a charged state of the battery pack, based on the generated data table.