PURPOSE: To completely and surely fit or remove a pump section during the inspection work of an internal pump by providing a grip section, an air cylinder, and a lock mechanism of the action of the piston rod of the air cylinder.

CONSTITUTION: A grip tool main body 57 is inserted at the position of the grip bolt 35 of an impeller 36, the tip of the bolt 35 is brought into contact with a detecting rod 72 to operate an underwater limit switch 67. The action is displayed on a control panel from the main body 57, and the state is reported to a worker on a platform. Air is fed into an air cylinder 58 by a control panel operation switch, and a piston rod 59 is pushed downward. A cylinder 62 is moved downward, and the bolt 35 is gripped by a hook 51. The handling tool 50 of an internal pump is hoisted by a hoisting rope 16. A lever 56 is changed from the opening action to the closing action as a frame 53 is moved upward, it is brought into contact with the upper disk 60 of the piston rod 59 from above, and the releasing action of the air cylinder 58 is mechanically locked.