To provide an inner surface polishing method of a work by inserting an extremely slight polishing material into the work having the cylindrical inner surface, efficiently polishing the inner surface.

The inner surface polishing method of a work inserts the polishing material A into the work 1 having the cylindrical inner surface and polishes the inner surface 9. The insert capacity of the polishing material A is set 5% or less of a space capacity in the work. Inner surfaces of various kinds of works can be speedily polished in a simple method without requiring specific equipment.