provided are a roll for roll forming and a roll forming method therefor , by which a strip of sheet material is continuously fed and passed between roll stands that are arranged continuously , and is sequentially formed so that the sectional shape of the sheet material becomes circular , and by welding both ends of the sheet material , a pipe is finally produced . in the method , pressure parts and non - pressure parts are selectively disposed on a convex roll or a concave roll and the frequency of pressuring by the convex roll and the concave roll is reduced or adjusted such that the work hardening of the roll formed material or produced pipe is lowered or made to be uniform . accordingly , the material characteristic and reprocessing characteristic of the roll formed material or pipe are greatly improved .