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The purpose of this study was to classify the overarm throwing motion of elementary-aged girls. Throwing motion of forty girls from sixth-grade was analyzed three-dimensionally. The z-score of joint angles was calculated as an index of deviation from a standard motion model and used as a variable for cluster analysis. Based on a distance between the clusters, the throwing motions of the sixth-grade girls were classified into three groups. One group had a throwing motion similar to the standard motion model, resulting in significantly longer throwing distances, while the other groups exhibited throwing motions that differed from the standard motion model, e.g., maximum external rotation of shoulder joint was low. These results indicate the potential effectiveness of the standard motion model as a reference in the evaluation of throwing technique.