PURPOSE: To provide a method and a device which enable insertion of an inspection probe, a sleeve, and an end plug by remedying the deformed end of the heat transfer pipe of a steam generator.

CONSTITUTION: The remedying device is used if the deformed end 100 of a steam-generator heat transfer pipe 40 is non-circular. The remedying device has a mandrel 190 shaped to engage with the inner surface 70 of the deformed end and a freely reciprocating drive 200 connected to the mandrel and exerting a reciprocating force on the mandrel in order to thrust the mandrel to bring it into close contact with the inner surface of the deformed end. When a reciprocating force is applied to the mandrel and the mandrel is engaged with the inner surface of the deformed end of the heat transfer pipe, the deformed end 100 of the heat transfer pipe is remedied and becomes circular.