A collision object protection device inflates and expands an air bag on a vehicle as soon as a collision of a collision object with the vehicle is detected or predicted. The collision object protection device includes: the air bag having a main body portion that expands along a lower part of a front windshield glass of the vehicle, a pair of pillar portions that expand along front pillars of the vehicle, and a pair of pillar base portions that connect the main body portion and the pair of pillar portions; and at least one inflator for supplying a gas to the main body portion of the air bag. A partition wall having one or more openings is arranged inside the air bag respectively at a boundary between the main body portion and the pillar base portion.