A colliding object protection apparatus inflates and deploys an airbag when the apparatus detects or predicts a collision with a pedestrian. The airbag includes a front bag to be inflated and deployed in a vehicle width direction along an upper part of a front grille of a vehicle. The internal space of the front bag is partitioned into a plurality of expansion chambers by a plurality of partitioning walls provided in parallel in the vehicle width direction. A vent mechanism of the expansion chamber is configured to be opened when an internal pressure of the expansion chamber reaches a predetermined pressure.