The purpose of this study was to investigate the developmental relationship between the image operation in three-mountain task and mental rotation task in terms of ability of a point-of-view operating. Subjects were 17 first graders, 18 third graders, 13 fifth graders and 31 university students. Subjects were asked to solve both three-mountain task and mental rotation task. The results showed a different shape of developmental performances in both tasks. In a three-mountain task, first and third graders could not perform satisfactorily, whereas in a mental rotation task, they could make good scores. Moreover, both patterns of errors and RT according to the rotated angles were also proved different between tasks.