PURPOSE: To provide a rotary die cutter which can sustain a satisfactory snip-off function even though a die is pressed against an anvil as abrasion of a cutter die progresses.

CONSTITUTION: A die 1 and an anvil 2 are arranged so that their axes A1, A2 are in parallel with each other, and are subjected to rotary motions around their axes A1, A2 in directions as indicated by the arrows X, Y, respectively. The die 1 and the anvil 1 against which the die 1 is pressed are rotated while a workpiece 7 is fed therebetween, and accordingly, the workpiece 7 is snipped off by the cutter die 6 of the die 1 and the straight cylinder-like peripheral surface of the anvil 2. The nearer to the center part of the die 1, the larger the diameter of the peripheral surface of the die 1, that is, the peripheral surface defines a convex curved surface. If the edge 3a of the cutter die 6 is worn, the edge 3a cannot reach the workpiece 7. Accordingly, the die 1 is pressed against the anvil 2 with a large force. In this phase, the die 1 flexes as shown by the one-dot chain line B. Since the peripheral surface of the die 10 is convex, the peripheral surface 9a of the die 1 on the anvil 2 side become substantially straight line-like, and accordingly, it is possible to prevent the peripheral surface 9a from being convex.