To provide a punching device that can appreciably reduce a fraction defective in blanking of a stripped sheet material.

The punching device comprises a blanking device 1 in which a punching edge is arranged for positioning in a horizontal plane to form a cut line shaped in correspondence with a shape of punched portions formed on a stripped sheet material 3 at given longitudinal pitches, and a mark detecting means 2 disposed upstream of the blanking device 1 with respect to carriage of the stripped sheet material 3 to detect a position of mark portions formed on the stripped sheet material 3 at given longitudinal pitches and in correspondence with the punched portions. The punching device further comprises a computing storing means 49 for computing and storing a movement correction level of the punching edge according to detection data on the position of the mark portions.