The purposes of this study were to investigate the overhand ball throw form considering the motion causality based on the collecting check points of previous studies and to apply the model to the throw form of elementary school children. The cause and effect analysis, one of the quality control methods, was applied to investigate the causal throwing motion. The motion was consisted from main two parts, rotational motion combined with the center of gravity movement and body axis twist-rotation including hand whip action. The twist and rotation motion preceded the whipping motion of throwing arms/hands, which was composed with throwing arm/hand motion and free arm/hand operation. Overhand tennis ball throw forms of 63 elementary school children(37 boys and 27 girls, 1-4 grade)were recorded on a video camera with 60 flames/sec. Based on the causal throw form, 54motions were observed by the video play. As the result of the principal component analysis, since the eigenvalue was 23.894and the contribution rate was 44.2%, the first component suggested the overhand throw form including both of detail motions and total evaluations. There were 7 variables with low loading(<0.3), which were verified for their cause and improvement.
