The current study aims to investigate whether there is a meaningful effect of self-efficacy and task value on the achievement approach goals in learning science. In line with this purpose, a correlational method was used in the current study. The participants of this study were 310 middle school students from six public schools (close to each other in terms of socio-economic level and opportunities) in different districts of Erzurum in Turkey. Data were collected through two previously validated instruments: The Achievement Goal Questionnaire and The Motivated Strategies for Learning Questionnaire (self-efficacy and task value subscales). The Achievement Goal Questionnaire was used to determine the students' approach goal orientations (mastery-approach and performance-approach) and The Motivated Strategies for Learning Questionnaire scale was used to assess the students' task value and self-efficacy perceptions. The data obtained were analyzed in two parts. In the first part, SPSS is used for descriptive statistics about variables. The structural Equation Model was used to test the proposed model in the second part. The results of the study have shown that self-efficacy and task value influence the level of students' mastery and performance approach goals. Besides, task value has a partial mediating effect on the relationship between self-efficacy and achievement approach goals. The results of the study were discussed according to the relevant literature.