To the outer edge of an electric shaver to be easily ground in high precision by providing an outer edge with an outer edge plate formed in a groove shape and an inner edge sliding inside the outer edge plate and equipping folded pieces protruded to both sides of the outer edge plate to combine the outer edge plate with a jig for inner face grinding in grinding the inner face of the outer edge plate.

A slit outer edge plate 2A with a U-shape section formed with a number of slits at equal intervals by a cutting disk has flashes protruding inside by cutting by the cutting disk. The slit outer edge plate 2A is mounted on a prescribed position for a jig 13 for inner face grinding for grinding the slit outer edge plate 2A from inside to remove flashes to make the inside flat. Folded pieces 2b for folding outside are protruded from both sides of the outer edge plate 2A to securely execute the mounting. The folded pieces are guided to engaging parts 13a of the jig 13 for inner face grinding to temporarily fix the outer edge plate 2A on a prescribed position of a fitting groove 14 of the jig 13 and inside grinding is carried out by a grinding disk 12 in that condition.