The purpose of the present study was to examine the relationship between motives for science learning and factors related to academic achievement in science by path analysis. Two hundred twenty-two junior high school students were given questionnaires on their perceptions of motives for science learning, and factors related to academic achievement in science, i. e., attitude for science(feelings for science), interest in and concern for biological teaching materials, and competence in science learning. Sub-dimensional components of motives for science learning was constructed. By applying factor analysis, four factors were found. Motives for science learning was evaluated by a mastery orientation scale, an activity orientation scale, a reality orientation scale, and a profit orientation scale. Based on previous work's model, a new causality model composed of four levels in science was constructed: attitude for science→interest in and concern for biological teaching materials→motives for science learning→competence in science. Through this analysis, the causal relationship between motives for science learning and factors related to academic achievementin science was revealed.