A seat back for vehicles including a seat back pad having supporting bodies fixed on a periphery of an opening or a seat frame, or formed integrally with the periphery of the opening by one or multiple-point support, the supporting bodies aligned at predetermined intervals, each arranged in a direction between periphery portions opposite to each other of the opening at a front surface portion formed as a backrest surface for a seated person, the supporting bodies being independent of each other in rod or plate form, each made of a synthetic resin foam having 20 mm or larger in bending deflection amount and 2 to 100 N in load when deflected by 20 mm measured in accordance with a method defined by JIS K7221-2:2006, and having an interspace portion configured such that the supporting bodies are allowed to be deformed by bending in a rear direction.