In this paper, we propose a motion control algorithm of a passive-type walking support system based on environment information. The passive-type walking support system we developed consists of a support frame, two casters, and two wheels with servo brakes. This system has a passive dynamics with respect to the force/moment applied to it, because it does not have any actuators for driving it, so that this system is intrinsically safe for using it based on the physical interaction between the system and the human being. In this research, we control the motion of the passive walker by adjusting the brake torque of each wheel based on the environment information, so that a user could avoid the collision with obstacles, prevent missing his/her step, and compensate the gravity of the system as if the user could use it safely on any roads such as the road with steep sloop. The proposed control algorithms are applied to passive-type walker referred to as RT Walker experimentally, and we show that RT Walker can be utilized successfully in environments such as the stairs, obstacles, and slops.