To provide a pipe polishing method capable of economically polishing an inner wall of a pipe of a various structure with a simple method and tool and an object used for it.

This method is provided with an object preparation process for preparing the object 10 having a solid of which surface is formed by a polishing material mixture foamed material 10a obtained by foaming a resin into which polishing material particles are mixed, and an object passing process for passing the object 10 through the pipe 1. The object 10 is a spherical or cylindrical body of which surface is covered by the polishing material mixture foamed material 10a at least, and an outside diameter of the object 10 is larger than an inside diameter of the pipe 1.