A passenger restraining device that restrains a passenger seated in a seat of a vehicle, comprising: a pair of airbags (120a, 120b) stowed in the inner portion on both the left and right sides of the seat that expand and deploy to the left and right of the passenger respectively, a left side tensile cloth and a right side tensile cloth that are stowed from within the seatback of the seat to within the seat cushion of the seat which deploys on exterior surfaces of each of the airbags (120a, 120b) during expansion and deployment of the pair of airbags (120a, 120b), and a lower tensile cloth that extends in the left-right direction in the inner portion of the seat cushion and connects the front ends of the left side tensile cloth and the right side tensile cloth, wherein the lower tensile cloth is disposed at least in the vicinity of the center in the left-right direction of the seat cushion, and further disposed more on the front side of the center of the seat cushion in the front-rear direction, the left side tensile cloth and the right side tensile cloth are disposed extending in both the left and right directions rearwardly from both the left and right ends of the lower tensile cloth in the inner portion of the seat cushion, and when the airbags (120a, 120b) expand and deploy, the left side tensile cloth and the right side tensile cloth deploy on the side part of the seat and are stretched between the seatback and the seat cushion characterized in that - the lower tensile cloth is shorter than the left-right direction width of the seat cushion, and - the left side tensile cloth, the right side tensile cloth an the lower tensile cloth are arranged in a trapezoidal shape with the fourth side removed when the seat cushion is viewed from above. a pair of airbags (120a, 120b) stowed in the inner portion on both the left and right sides of the seat that expand and deploy to the left and right of the passenger respectively, a left side tensile cloth and a right side tensile cloth that are stowed from within the seatback of the seat to within the seat cushion of the seat which deploys on exterior surfaces of each of the airbags (120a, 120b) during expansion and deployment of the pair of airbags (120a, 120b), and a lower tensile cloth that extends in the left-right direction in the inner portion of the seat cushion and connects the front ends of the left side tensile cloth and the right side tensile cloth, wherein the lower tensile cloth is disposed at least in the vicinity of the center in the left-right direction of the seat cushion, and further disposed more on the front side of the center of the seat cushion in the front-rear direction, the left side tensile cloth and the right side tensile cloth are disposed extending in both the left and right directions rearwardly from both the left and right ends of the lower tensile cloth in the inner portion of the seat cushion, and when the airbags (120a, 120b) expand and deploy, the left side tensile cloth and the right side tensile cloth deploy on the side part of the seat and are stretched between the seatback and the seat cushion - the lower tensile cloth is shorter than the left-right direction width of the seat cushion, and - the left side tensile cloth, the right side tensile cloth an the lower tensile cloth are arranged in a trapezoidal shape with the fourth side removed when the seat cushion is viewed from above.