To provide a metal sheet drum cutting device which can reduce the generation of burrs, form burrs in an easily removable manner, and enables the rapid cutting with high accuracy, and a cutting method thereof.

This metal sheet drum cutting device comprises a rotatable blade-setting roll 22 abutted on an outer circumferential side surface of a metal sheet drum 2 and a cutting blade roll 24 which is cut in and rotatable along a side wall of the blade-setting roll 22 from the inside of the drum corresponding to the blade-setting roll 22 and advancing/retractable in the radial direction of the drum 2. It further comprises a pressing means 28 for pressing the cutting blade roll 24 and advancing it in the cutting-in direction, and a driving means 20 for integrally rotating the blade-setting roll 22 and the cutting blade roll 24 in the circumferential direction of the drum 2.