An automatic brake system for a vehicle is disclosed. Based on a possibility that a potential collision with an obstacle preceding the vehicle can avoided by braking, and a possibility that the potential collision can be avoided by steering, the system automatically controls a braking operation for collision-avoidance. A condition of starting the automatic braking operation and a characteristics of the operation are determined based on calculation or estimation of a condition of the path where the vehicle is traveling, such as a relative speed, widths of spaces on sides of the obstacle, and steering characteristics.