In this paper, we introduce a concept of passive robotics for realizing a physical interaction between a human and a robot safely, and also present two types of the intelligent mobile robot with servo brakes which are developed based on the passive robotics. One is the passive-type intelligent walker referred to as RT Walker for assisting the walking of elderly people, handicapped people, and blind people. The other is the passive-type object transportation system referred to as PRP, which realizes the assistances of the transportation of a large and a long object. Both systems consist of wheels with servo brakes, controller, and rechargeable battery. By controlling the servo brakes appropriately, many kinds of function for assisting the humans could be realized without using the active actuators such as servo motors.