An occupant protection apparatus for a vehicle includes a first power source means, a second power source means for supplying power of higher voltage than that of the first power source means, a collision-predicting means for predicting a collision, a driving means for driving an actuation mechanism of the vehicle on the basis of an output from the collision-predicting means, and a switching means for switching over from the first power source means to the second power source means for supplying power to the driving means when a collision is predicted to occur by the collision-predicting means.