The purpose of the present invention is to provide a cushion structure for a vehicle seat, the cushion structure allowing the hardness of the cushion to be adjusted according to an occupant's preference by simple operation. The present cushion structure for a vehicle seat has: a band (41) consisting of a flexible material, the band (41) being provided below the lower surface (1b) of a cushion foam and extending in the longitudinal direction of the seat; and a tension adjusting mechanism (5) for adjusting the tension of the band (41) consisting of a flexible material. The tension adjusting mechanism (5) adjusts the hardness of the cushion foam (1) by adjusting the tension of the band (41) consisting of a flexible material.