Seat of a vehicle with an occupant restraining device (100,200) that restrains an occupant sitting on the seat of a vehicle, comprising: an airbag (120a, 120b, 220a, 320a) stowed in the seatback of the seat that expands and deploys to the side of an occupant seated in the seat; a tensile cloth (130a, 130b) stowed from within the seatback of the seat to within the seat cushion along the side of the airbag (120a, 120b, 220a, 320a), on the side opposite the occupant; wherein the tensile cloth (130a, 130b) is deployed along the side of the seat on the side opposite the occupant by the expansion and deployment of the airbag (120a, 120b, 220a, 320a) by breaking the surface skin of the seat, and is stretched from the seatback to the seat cushion to retain the surface of the airbag (120a, 120b, 220a, 320a), characterized by an angle detecting means that detects the reclining angle of the seatback, and internal pressure control means for controlling the internal pressure of the airbag (120a, 120b, 220a, 320a) during expansion and deployment according to the reclining angle, and a dual inflator (160, 160a, 160b, 160c) including first and second inflators (162, 162a, 162b, 162c, 164, 164a, 164b, 164c) that supply gas to the airbag (120a, 120b, 220a, 320a), wherein the internal pressure control means controls the internal pressure of the airbag (120a,120b, 220a, 320a) by the dual inflator (160, 160a, 160b, 160c), delaying the gas discharge timing of the second inflator (164, 164a, 164b, 164c) from that of the first inflator (162, 162a, 162b, 162c), wherein when the internal pressure control means determines that the seatback is in the driving position the first inflator and the second inflator are ignited simultaneously, and when the internal pressure control means determines that the seatback is in the maximum recline angle position, only the first inflator is ignited, until the airbag (120a,120b,220a,320a) has completed expansion and deployment and has finished restraining the occupant, and thereafter the second inflator is ignited. and when the internal pressure control means determines that the seatback is in an intermediate reclining position between driving position and maximum reclining angle position the first inflator is ignited first and the second inflator is ignited after a delay during expansion and deployment of the airbag (120a, 120b,220a,320a). an airbag (120a, 120b, 220a, 320a) stowed in the seatback of the seat that expands and deploys to the side of an occupant seated in the seat; a tensile cloth (130a, 130b) stowed from within the seatback of the seat to within the seat cushion along the side of the airbag (120a, 120b, 220a, 320a), on the side opposite the occupant; wherein the tensile cloth (130a, 130b) is deployed along the side of the seat on the side opposite the occupant by the expansion and deployment of the airbag (120a, 120b, 220a, 320a) by breaking the surface skin of the seat, and is stretched from the seatback to the seat cushion to retain the surface of the airbag (120a, 120b, 220a, 320a), characterized by an angle detecting means that detects the reclining angle of the seatback, and internal pressure control means for controlling the internal pressure of the airbag (120a, 120b, 220a, 320a) during expansion and deployment according to the reclining angle, and a dual inflator (160, 160a, 160b, 160c) including first and second inflators (162, 162a, 162b, 162c, 164, 164a, 164b, 164c) that supply gas to the airbag (120a, 120b, 220a, 320a), wherein the internal pressure control means controls the internal pressure of the airbag (120a,120b, 220a, 320a) by the dual inflator (160, 160a, 160b, 160c), delaying the gas discharge timing of the second inflator (164, 164a, 164b, 164c) from that of the first inflator (162, 162a, 162b, 162c), wherein when the internal pressure control means determines that the seatback is in the driving position the first inflator and the second inflator are ignited simultaneously, and an angle detecting means that detects the reclining angle of the seatback, and internal pressure control means for controlling the internal pressure of the airbag (120a, 120b, 220a, 320a) during expansion and deployment according to the reclining angle, and a dual inflator (160, 160a, 160b, 160c) including first and second inflators (162, 162a, 162b, 162c, 164, 164a, 164b, 164c) that supply gas to the airbag (120a, 120b, 220a, 320a), wherein the internal pressure control means controls the internal pressure of the airbag (120a,120b, 220a, 320a) by the dual inflator (160, 160a, 160b, 160c), delaying the gas discharge timing of the second inflator (164, 164a, 164b, 164c) from that of the first inflator (162, 162a, 162b, 162c), wherein when the internal pressure control means determines that the seatback is in the driving position the first inflator and the second inflator are ignited simultaneously, and when the internal pressure control means determines that the seatback is in the maximum recline angle position, only the first inflator is ignited, until the airbag (120a,120b,220a,320a) has completed expansion and deployment and has finished restraining the occupant, and thereafter the second inflator is ignited. and when the internal pressure control means determines that the seatback is in an intermediate reclining position between driving position and maximum reclining angle position the first inflator is ignited first and the second inflator is ignited after a delay during expansion and deployment of the airbag (120a, 120b,220a,320a).