To realize the automatic creation of an environmental map using a mobile robot, i) accurate positioning of the mobile robot itself and ii) accurate and reliable measurements of the relative positions of the surroundings are requisite. However, conventional methods for i), such as dead-reckoning or the placement and measurement of several landmarks, have low accuracy of position measurement. In addition, some typical devices that are used for ii), such as CCD cameras, ultrasonic sensors, and laser range finders, are likely to produce inaccurate measurements depending on lighting conditions and problematic objects, such as mirrors. In this paper, a new method named "Map Creation by CPS Based Active Touch" that is able to create an environmental map with high accuracy and reliability is proposed. This method employs the "Cooperative Positioning System (CPS)" that we have proposed for mobile robot positioning and "active touch" that is able to gather highly reliable information from a robot which contacts its surroundings as it moves. Furthermore, we propose a bumper mechanism that can be utilized not only to absorb shock but also to realize purely mechanical wall following behavior. Experiments in an indoor environment show that the proposed method is able to create an accurate environmental map of the positions of major features such as walls, pillars and doors.