Protection apparatus includes: a seat back pivotable between reclined and upright positions; a pivoting-angle adjustment section for adjusting the pivoting angle of the seat back through a motor; a prediction section for predicting an object likely to collide against the vehicle from behind; a control section for controlling the adjustment section, in accordance with a prediction signal generated by the prediction section, to cause the seat back to be pivoted to a practically vertical upright position. The control section is arranged to control the adjustment section in accordance with not only the prediction signal but also an operation signal from a manual seat operating section. When the prediction signal has been received, the control section controls the adjustment section to cause the seat back to be pivoted to the practically vertical upright position at higher speed than when the operation signal has been received.