Abstract: An offset-shaped fin 4 can be continuously processed by roll molding by a method involving a first step of bending a flat sheet-like material 40A into a concavo-convex shape by a pair of first rollers 5, 5? to form a corrugate sheet 40B; a second step of cutting slopes of the concavo-convex ridges of the corrugate sheet by a pair of second rollers; and a third step of bending the offset portion, offset and cut in the second step, by a pair of third rollers. A pitch-changing method of offset-shaped fins involves a step of supplying offset-shaped fins between at least one pair of pitch-changing rollers rotating while meshing with the other so that at least one pair of pitch-changing rollers clamp the offset-shaped fins between them, allow them to pass through said pitch-changing rollers and change their pitch.