Two people usually walk through a corridor in a parallel position. However, they spontaneously switch their positions from the parallel to the cascade position when they pass oncoming people. We propose a method for enabling a robot to switch the parallel and the cascade positions autonomously with the movement of oncoming people and obstacles when it moves with a user in a daily environment. The robot uses two laser range finders to detect walls, the user's position, as well as surrounding people and obstacles. It autonomously decides whether to go on ahead or to give way to the user. Experimental results using a robot in a daily environment show that our method was effective.