A passenger restraint system for roller coasters, designed to maintain a passenger in an essentially upright posture, the passenger restraint system including a fixed column and a seat column designed to support and hold the passenger, which seat column is coupled to the fixed column so as to be movable relative to the fixed column and to be adjustable to the size of the passenger during an embarkation phase. The seat column is coupled to the fixed column by an articulated linkage, and the passenger restraint system further includes a device for balancing the seat column, which balancing device includes a cylinder fixed, at a first articulated end, to the fixed column and, at a second articulated end, to the seat column.