The goal of both automakers and vehicle users is to minimize the negative impacts of vehicles on society, such as traffic accidents, not only on the road but parking area, optimizing the enjoyment of using a car, comfort, and usability. To realize this, we have already provided automatic brake system (ICS) for static obstacles in parking area. We have also developed the Rear Cross Traffic Auto Brake (RCTAB) system, which detects a vehicle approaching from the sides when backing out of a parking area. We decided RCTAB system specifications based on two information “Approaching vehicle speed in parking area” and “Maximum backing speed”. RCTAB system structure consists of Radar which shared with “Blind Spot Monitor” and ECU which shared with “ICS Computer”. The radar detects the approaching vehicle. The ICS Computer judge Collision prediction and request “Braking Force” and “Driving Force” to Brake and Engine Computer. Collision predictive judgment by ICS Computer uses the information about predictive course of approaching vehicle and driver’s vehicle. The predictive course of approaching vehicle is calculated using positional information history of the vehicle (Position, Speed, Acceleration). When the two courses cross, ICS Computer judges “Collision” in future. When ICS Computer judges “Collision”, ICS Computer calculates “Time-To-Collision (TTC)” and “Necessary time to Stop of driver’s vehicle”, and compares them. If TTC is shorter, ICS Computer requests Driving force and Braking force. This control logic prevents the early system activation. If system activates too early, the driver feels uneasiness if approaching vehicle changes its course not to collide. We evaluated some back out scenes in parking area.