The present disclosure relates to a vehicle airbag device, which includes a main cushion and an auxiliary cushion deploying from the main cushion and may more effectively protect both a passenger-seat passenger in a normal seating state and a passenger-seat passenger in a relaxed seating state even in the event of an oblique offset collision by differentiating the deployment of the auxiliary cushion by releasing or maintaining the connection of a tether connected to the auxiliary cushion during deployment of an airbag cushion.