Disclosed is a fin processing apparatus including an upper pressing die (1) and a lower pressing die (2) placed apart from each other and capable of coming close to and away from each other, a corrugating mechanism (3) disposed between the pressing dies (1, 2) for continuously forming a plurality of consecutive corrugated members (Fa) from a flat plate (Fo) which is a workpiece material, the consecutive corrugated member (Fa) having a predetermined number of crest portions, and a restriking mechanism (4) disposed between both pressing dies (1, 2) for simultaneously restrike-forming a plurality of crest and trough portions of the consecutive rectangle member (Fb) from the consecutive corrugated member (Fa). The corrugating mechanism (3) and the restriking mechanism (4) are provided integrally.