The purpose of this paper is to clarify the historical developing process from the mid 1870s when baseball came in, to 2008, about the movement of the overhand pitch that is one of techniques of the pitcher in baseball. The result of this study can be outlined as follows. 　 When baseball came to Japan in the beginning of the 1870s, the pitcher must pitch the ball in an easy underhand motion. In 1895, American rules were translated into Japanese for the first time the history of overhand pitching started at this time. However, there was no pitcher's mound, therefore, the pitcher must generate the power of the ball by himself. As a result, torso movement that inclined toward second base, and, inclined toward home base developed. 　 In 1905, a new rule was introduced to Japan. This rule provided for the height of pitcher's mound to a maximum height of 15 inches. This change made the pitcher more able to throw down from a high position. As a result, the movement that inclined toward home base was emphasized. One more reason of this emphasis was the location of the strike zone. It was identified between a batter's knees and his shoulders on the basis of a vertical posture, therefore, a speedball up to the height of the shoulder was a good ball. To throw that kind of ball, movement like that was required. 　 At the end of the 1920s, the twisting of the waist during an arm swing was generalized. In addition, combination of the torso movement and limbs was utilized. There was gradually an increase of the attention to ball control behind this development. 　 From a rule of 1941, the pitcher was permitted to step back behind the pitcher's plate, before stepping to home base. As a result, the pitcher came to be able to make more of a driving force to the home base direction by rising up his leg up extremely high. In order to generate this power, a follow up movement developed; the twisting torso to the second base direction and s twist back to the home base direction. 　 In 1956, the strike zone was reduced to between the batter's knee and his "arm pits", on the basis of the "batting posture". As a result, the effect of the speedball in relation to the height of the shoulder came to be called "ball" which means not a strike. And throwing to the lowest height came to be the most important factor, therefore, the movement of the inclining torso which was seen since the beginning, came to be ineffective. And pitching in an inclined movement changed to a vertical movement of the torso. Because of this change, the subject of the pitcher changed from aiming to create big power pitches into stabilizing the control of the pitch. 　 In 1988, the height of the pitcher's mound was reduced from a height of 15 inches to 10 inches. Next year, the upper limit of the strike zone was dropped from "armpit" to "horizontal line at the midpoint between the top of the shoulder and the top of the uniform pants". In 1997, the lower limit of strike zone was dropped to beneath the kneecap. For those reasons, the pitcher began to put emphasis on control, especially, throwing the lowest ball became the most important subject, more so than before. To throw a lower ball, stability of movement was taken into consideration as well. This resulted in the twisting to the second base direction that had been seen since about the 1940s to become ineffective for the first time. And then, the movement of the arms and legs, such as a forward step with a twisting inward motion, a backswing whilst lifting an elbow, a forward swing with a torsion movement and the return of it, developed. As a summary, the vertical torso movement and the twisting direction to home base is the conventional movement technique of modern day overhand pitching of baseball.

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