A braking apparatus for a vehicle is provided which includes a hydraulic booster to make wheels of the vehicle produce frictional braking force, a solenoid valve, and a collision avoidance controller. The solenoid valve selectively exerts the hydraulic pressure of brake fluid stored in an accumulator on a spool valve in the booster. When determining that there is a risk of a collision with an obstacle, the collision avoidance controller opens the solenoid valve to achieve emergency braking to minimize the risk of the collision. Basically, emergency braking is achieved by installing the solenoid valve to selectively exert the hydraulic pressure on the spool valve, thus allowing an emergency avoidance braking system to be constructed with a minimum of equipment and facilitating the mountability of the braking apparatus in the vehicles.