This invention provides a seat back that adequately ensures the thickness of the headrest
cushion to enhance protection for the head or neck of the occupant. The seat back of this invention includes: a seat back frame (10) serving as the skeleton of the seat back; a headrest (30) supporting the head of the occupant; and a headrest post (40) attached to the upper part of the seat back frame and supporting the headrest, wherein the headrest post has: a fixing portion (41) fixed to the upper front surface of the seat back frame; and a first curved portion (42) extending rearward from the fixing portion.