The present invention relates to an internal pump. A water hole (33) allowing communication between internal and external circumferences of a stretch tube (24) is provided at the portion of the stretch tube corresponding to a position where an end face of a nozzle portion (14a) of a motor case (14) and an end face of a diffuser (13) are joined with each other so that hot filtered water inside a pressure container (1) which has entered from where the end face of the nozzle portion (14a) of the motor case and the end face of the diffuser (13) are joined with each other is combined with the purged water so that it can be sent back to the pressure container (1) again.
