The purpose of this study was to compare the EMG activities of four-forearm muscles during Kumdo head striking. The four skilled and unskilled Kumdo club members were selected from D university in B city. Investigated muscles were left brachioradialis, right brachioradialis and left flexor carpi radialis, right flexor carpi radialis. Raw EMG data were collected during the head striking motions and the average EMG were calculated by the frame width of 0.05s, and then the average %MVC were calculated. The average %MVC values of each muscle in each group were compared. The results are as follows. 1) In each group, there were no significant statistical differences between every muscle over the all phases. 2) There were significant differences, however, between skilled group and unskilled group. The former got higher average %MVC at left flexor carpi radialis and the latter at right brachioradialis in the ready phase and in the impact phase.