A brake pedal apparatus for a vehicle is provided. The brake pedal apparatus includes a fixing bracket fixedly installed in a vehicle, a pedal arm coupled to the fixing bracket to be rotatable about a first axis, and a collision rack coupled to the fixing bracket to be rotatable about a second axis which is different from the first axis. The collision rack is configured to rotate upon a collision with a collision bracket. The fixing bracket supports the pedal arm to allow the pedal arm to be movable in a predetermined direction. The collision rack blocks the movement of the first axis of the pedal arm, and upon the collision with the collision bracket, the collision rack allows the pedal arm to be disengaged from the fixing bracket, thereby reducing the risk of injuring the driver.