An occupant restraining device that can maintain the internal pressure of a bag at a high level is provided. A bag 12 has its left and right ends both provided with stationary sections 12a and 12a that are fixed to a seat pan 8. The stationary sections 12a and 12a have therebetween a gas chamber 15 that is inflated as a result of gas entering from an inflator 13. The bag 12 is made into the form of a pouch by stacking an upper panel 16 and a lower panel 17 one on top of the other, which are to respectively define an upper half and a lower half of an outer periphery surface of the bag 12 in an inflated state, and then bonding and sewing these panels together along the edges thereof. Specifically, the bonding of these panels together along the edges thereof involves the use of elastic adhesive 19 having a stretchability of 200% or more, for example, between 200% and 400%.