The purpose of this study was to investigate the bat swing parameters that determine the flight distance and the kinetic energy of batted ball in baseball batting. Thirteen collegiate baseball players performed free-batting practice with maximal effort in the direction of center field. Behavior of ball and bat around impact were recorded with an ultra-high-speed camera (2500 fps) and a tri-axial gyro-sensor (1000 Hz) attached to the grip end of a wooden baseball bat. Flight distance was correlated with the velocity of the batted ball immediately after impact (r = 0.79, p < 0.01) and the velocity of the ball spin after impact (r = －0.43, p < 0.05). Stepwise multiple linear regression analysis found that flight distance was independently associated with the velocity of the bat head and the angle of the bat swing from horizontal line immediately before impact, and that the kinetic energy of the ball immediately after impact was independently associated with the velocity of the bat head (R² = 0.52, SEE = 7.40 m), the angular velocity of the long axis of the bat (Rolling angular velocity) and the angle of the bat swing from horizontal line immediately before impact (R² = 0.63, SEE = 9.87 J). These results suggest that the high velocity of the bat head and the large angle of the bat swing from horizontal line immediately before impact is important to hit a ball further, moreover the high rolling angular velocity is needed to increase kinetic energy in addition to two parameters mentioned above.