To provide a corrugated fin cutting device and method for cutting a corrugated fin material having each ridge line part corrected to a crest-shape.

This cutting device is provided with a pitch enlarging means 2 for enlarging fin pitch of a crest-shape projecting part position 11d in the fin material 11 since each of the ridge line parts 11c forcibly fits into a valley part 11b of the corrugated fin material 11 corrected to the crest-shape, a cutting guide means 3 for performing positioning by pressing a cutting position by inserting into the trough part 11b enlarged with pitch along the pitch enlarging means 2, and a fin cutting means 4 constituted of a fixed blade 41 arranged on a rear face side of the valley part 11b enlarged with pitch and a movable blade 42 for shearing the valley part 11b in a space with the fixed blade 41 by inserting into the valley part 11b enlarged with pitch along the cutting guide means 3.