The objective of the present invention is to provide an assistance suit (10) which achieves simultaneously both the effect of correcting posture and the effect of assisting a forward bending action, which has a satisfactory feeling when worn, and which imparts little sense of resistance to day-to-day actions performed by the wearer. To this end, a spine member (20) for an assistance suit comprises a plate-shaped member which has a vertically long shape extending from the back of the user to the buttocks of the user, is curved along the back of the user, is resilient in the bending direction, and the width of which differs in the longitudinal direction. The spine member is provided either with one part, above a central portion in the longitudinal direction of the spine member, having a width that it less than the width of other parts, or one part, above the central portion in the longitudinal direction of the spine member, in which the width in the vicinity of the scapula at the back of the wearer is less than the width of other parts.
