Effective robot functions emerge from not only according to the level of system control i. e. intelligence but also according to conformity between morphology, intelligence, task and environment. We have been analyzing and investigating the relationship between morphology and intelligence acquired through the difference of tasks and the characteristic differences of functions emerged from the balance between them. In this paper, a simulation of a task in which the robot had to maintain a certain distance from an object is executed. As robotic morphology, we use visual sensors changed its position through evolution by genetic programming : GP and robotic intelligence described as a decision tree is also evolved by GP. The results clarified the importance of balance between morphology and intelligence and showed effective functions emerged as the result of such balance.