To provide an air bag device for a wheelchair capable of absorbing an impact on a user not only when the wheelchair overturns but also when the wheelchair collides with an object.

This air bag device is so constituted as to inflate an air bag 13 when an inclination sensor 11 detects the inclination of the wheelchair 1 or a collision sensor 12 detects the collision of the wheelchair 1, so that this wheelchair can absorb the impact on the user not only in the overturn of the wheelchair 1 but also in the collision of the wheelchair 1 and is effective as a means for protecting the user A in the wheelchair 1 from the overturn accident and the collision accident.