Six basic generations, P1, P2, F1, F2, BC1 and BC2 of one azuki bean cross, Hondawase × Akatsukidainagon, were planted at two locations on the highland area of Chiang Mai province for two consecutive growing seasons. The objective of the study was to evaluate the gene action as influenced by environmental variations on seed yield per plant and number of pods per plant of azuki bean by using the generation mean analysis. Results of the study indicated that there were additive gene effect, dominance gene effect and interaction of both genes effects of these studied traits with environment. This study suggested that seed yield per plant and number of pods per plant were important agronomic characters which highly responded to environmental variations, thus, optimum environmental factors especially low temperature on highland areas should be selected for testing gene action in azuki bean.