PURPOSE: To provide a pitch adjusting device for a corrugate fin for a heat exchanger having self-diagnostic function to detect spring back when a pitch is adjusted and the like, capable of automatically not only compressing but also extending a pitch to set a desired pitch and highly automated.

CONSTITUTION: Extending or compressing a pitch of fin is executed by making required different revolution between two couples of pinching rollers to obtain the target number of corrugate fins stored between fore rollers R1 and aft rollers R2. For instance, the discharging pitch is extended from the supplied pitch by reducing the number of fins stored between the pinching rollers R1 and R2, the number of peak parts per a unit length is calculated in real time by a counting sensor PHS2 by which the number of peak parts on a material to be worked 1 after discharged from the after pinching rollers R2 and the measuring of length by a measuring roller RE and the speed of the after pinching rollers R2 is feedback controlled.