In Japan, there are two major baseball competitions, which are baseball and rubber-ball baseball. Players are often confused by the difference because many baseball players go through the transition between those competitions. Purposes of this study were to reveal the difference of the characteristics of the balls for baseball and rubber-ball baseball when those balls are hit by a metal baseball bat and to research experienced perception of the baseball players toward the difference. A bat swing robot was used for researching physical characteristics of those batted balls under stable condition with changing the vertical offset between the center of a bat and that of a ball. As a result, a rubber-ball recorded maximum range by smaller offset than a baseball and it also tended to generate larger vertical angle and smaller speed of the batted ball. Furthermore, the result of the robot test corresponded to the experienced perception of baseball players, which was revealed by a questionnaire.