PURPOSE: To execute every bending by an operation of once, by moving a holding roll in the prescribed direction in accordance with an extent of feed-out of a material to be worked, when bending a long-sized material.

CONSTITUTION: One or both of a feed-out roll 11 and a bending device body 20 provided with a holding roll 61 are constituted so as to move back and forth continuously in the feed-out direction of a material to be worked M, or so that the speed can be changed. Also, the holding roll 61 of the bending device body 20 moves independently in the horizontal direction and the vertical direction falling at right angles with a feed-out direction of the material to be worked M in accordance with its feed-out distance, or particularly, in the circumferential direction, respectively, and executes desired bending in the feed-out direction, that is, in the length-wise direction of the material to be worked M. Accordingly, bending of the material to be worked M can be executed continuously, and a product is obtained by cutting said material to desired length by a specified- length cutter 70, etc.