The present invention provides an ink jet printing apparatus capable of improving reliability of an electrical connecting portion between a carriage side and head cartridge side. When an ink tank is mounted on a head cartridge, a hook of a set lever is obstructed to be operated in a lock releasing direction by a restricting surface of the ink tank. This prevents the head cartridge from being removed from the carriage, and maintains an electrical connecting condition between the carriage and the head cartridge. Therefore, for removing the head cartridge, it is necessary to remove the ink tank.