This study was attempted to investigate the relationship between the academic achievement and the internal and external motivation of academic achievement. Here, the internal motivation of academic achievement refers to the case that a student feels the necessity of study and h satisfaction, expects rewards, or has interest in his study; external motivation of academic achievement means that a student has outward motivation such as other"s recognition, rewards, or compulsion. As the result of this study, there showed significant difference in the academic achievement in proportion as the level of internal and external academic achievement motivation (P<.001). the students with the higher internal motivation and the lower external motivation turned out to have the highest effect of academic achievement; on the other hand, the students with the lower internal motivation and the higher external motivation showed the least academic achievement. There was 11.60 points-difference on the average between those two groups in terms of grade. The academic achievement and the internal motivation shows significant correlation(r=.25, P<.001) while academic achievement and the external motivation presents negative tendency (r=-.10). Through the results of regression analysis, the estimation of the academic achievement by the two variables to academic achievement motivation was 6.22%(P=.0001)