To provide a device for polishing the internal surface of a long pipe, which achieves reduction of a diameter of an operating portion inserted into the long pipe, and is available for polishing a long pipe having a small diameter.

The operating portion 100 of the device, inserted into the long pipe, has a fixing means A to be fixed to the pipe internal surface, and a rotary brush means B. The fixing means A includes clamp arms 2 to 4 expandable and collapsible depending on reciprocation of an operating rod 1a of a cylinder 1. The rotary brush means B is attached to a distal end of the fixing means A. The clamp arms 2 to 4 have their proximal ends 2a to 4a rotatably attached to the operating portion 100, and the proximal ends 2a to 4a have engaging portions 2c to 4c formed therein, respectively. Further the operating rod 1a of the cylinder 1 has a spoke 10 connected thereto, and engaging pieces 10a formed on the spoke 10 engage with the engaging portions 2c to 4c of the proximal ends 2a to 4a, respectively. Then by reciprocating the operating rod 1a of the cylinder 1 to linearly move the spoke 10, the clamp arms 2 to 4 are expanded and collapsed.