To easily provide a grinding device having a wide operation range by a method wherein a wide space is provided radially externally of a rotary saw.

This saw teeth feeding device comprises a motor to rotate a rotary saw 10; a positioning device 15 to support a tooth 10a-1 scheduled to be ground by fitting a positioning element 21 in a space between the tooth parts of the grinding portion of the rotary saw 10; a braking device 25 to block rotation of the positioned rotary saw 10; an indexing drive part to indexing rotation of a feed motor 9; a positioning device drive command part to fit a positioning element 21 in a space between the teeth part of the grinding portion of the rotary saw 10 after rotation by the indexing drive part; an advance drive part to rotate the feed motor 9 in a direction, in which the tooth, scheduled to be ground, of the rotary saw 10 is moved toward the positioning element 21, after the positioning element 21 is fitted in a space between the teeth of the grinning portion of the rotary saw 10; and a braking device drive command part to issue an operation command to a brake device 25 after the tooth scheduled to be ground makes contact with the positioning element 21.