PURPOSE: To provide an economical manual grinder with a grinding portion easily replaceable and reversible by using a thin plate coated with abrasive materials for multiple applications.

CONSTITUTION: A manual grinder 10 for polishing a sharp-edged tool including a knife and a chisel and grinding and sharpening the surface has two ferromagnetic rails 18 spaced from each other with upper ends located on the same plane. A magnet 14 is arranged between both rails together with a ferromagnetic plate 20 magnetically held on the rails. The plate 20 has a grinding surface coated with abrasive materials 22, a magnetic flux of the magnet is intensively guided to the plate 20 via the rails 18 and the rails 20 are held in place at the upper ends of the rails without being offset.