Abstract
Strains of nails before and after ball-release of baseball pitch were measured with strain gauges affixed on nails of 2nd and 3rd fingers. The measurements of strains were executed during simulating ball-release of straight ball, shoot ball and slider ball pitches, and actual pitching. The characteristics of strain of nails before and after ball-release were clarified and the possibility for understanding the state between fingertip and ball was suggested.