The present study aimed to examine the effects of uchikomi movement (a throwing drill) in seoi-nage (shoulder throw) training on the strength and thickness of the quadriceps femoris (QF) in elementary judo players. The subjects were seven boys and one girl aged 10 12 years. They had a control period of 12 weeks, and then participated in uchikomi movement in seoi-nage training (100 repetitions / day, 3 days / week, 12 weeks). Before and after the period of control and training, the isometric knee extension torque per body mass (KET / BM) during maximal voluntary contraction and the thickness of the QF were determined. The KET / BM and the thickness of the QF increased significantly after training intervention. Moreover, relative changes of the KET / BM were negatively correlated to the absolute values before the intervention. Thus, the results indicate that, the uchikomi movement in seoi-nage training can be an exercise modality for improving the force-generating capability of the QF in elementary judo players. However, the magnitude of the improvement is influenced by the force-generating capability before the intervention.