The invention discloses an airbag device for a wheel, and relates to the field of safety devices for vacuum tires. A tire pressure monitoring device is installed on a wheel hub of the wheel, a gas generator is arranged on a wheel rim of the wheel hub, a supporting airbag which can be filled in a tire after inflation is connected to the gas generator, the tire pressure monitoring device is connected with an electronic controller, and the electronic controller is connected with a starting device of the gas generator; the gas generator is structurally characterized in that a barrel-shaped outer shell with an open front end is arranged, a propellant is contained in the outer shell, an igniter of the propellant is arranged in the outer shell, and the supporting airbag is arranged at the front end of the outer shell; and the supporting airbag is stacked in a fragile airbag shell when not inflated, and the airbag shell is fixedly connected with the outer shell. According to the airbag device,when the tire is damaged, the shape of the tire can be restored, so that a vehicle can normally run and brake, and secondary accidents caused by sudden tire burst can be avoided.