Abstract: An automatic grinding apparatus for wood working comprising means for maintaining substantially constant the contact pressure between a grinding wheel and a material to be ground and the peripheral speed thereof irrespective of abrasion of the grinding wheel. The means for maintaining the contact force constant comprises a grinding wheel swinging means and a grinding wheel compensating means. The former includes a swing arm pivotally mounted on a slider for swinging movement and carrying rotatably a grinding wheel shaft at the free end, and a cylinder means for swinging the swing arm toward and away from the material. The latter includes a means for detecting the angular displacement of the swing arm due to abrasion of the grinding wheel and a slider moving means for advancing the slider toward the material until the swing arm restores to its initial angular position.