Background: Students' motivation generally declines over time. Some researchers have suggested that the parallel decline in academic self-efficacy and values may be as a result of the longitudinal reciprocal relations between these two motivational constructs. However, little empirical evidence has supported this speculation. Further, all prior evidence has been provided based on samples of students from Western countries (Europe, United States). Aims: The current study was designed to examine the reciprocal relation between academic self-efficacy and values with a sample from another culture, namely South Korea. Sample: We used nationally representative longitudinal data of 6,908 students in seventh grade (M[subscript age] = 12.83 years). Methods: We analysed the data tracking our sample from 7th grade to 11th grade. Latent cross-lagged models of academic self-efficacy and values in mathematics and English for 5 years were tested, while controlling for gender, achievement, and family income. Results: In both mathematics and English domains, there emerged significant unidirectional paths from prior values to later self-efficacy from Grades 8 to 11. For English, significant unidirectional paths from prior self-efficacy to later values additionally emerged from Grades 8 to 9. That is, significant reciprocity between self-efficacy and values was found for English from Grades 8 to 9. Conclusions: Relatively consistent paths from prior values to later self-efficacy were identified among Korean adolescents, distinct from prior work focusing on students from Western countries. The results underscore the importance of considering different educational contexts and suggest the critical role of values in the development of Korean adolescents' academic self-efficacy.