A side collision airbag device includes an airbag to inflate and extend between a side wall portion of a vehicle and an occupant seated on a seat disposed in the vehicle. An inflator is connected to the airbag to spout a gas for inflating and extending the airbag from one side thereof in its longitudinal direction. A restricting member is attached for restricting a movement of the inflator toward the other side thereof in its longitudinal direction when the inflator is activated.