Disclosed herein is a method of manufacturing one or more kinds of rectangular unit pieces from a long base material sheet at a predetermined angle through a continuous cutting process using a cutting frame, the method including (a) manufacturing a base material sheet of a laminate structure having two or more stacked sheets and winding the base material sheet on a roll, (b) continuously feeding the base material sheet, wound on the roll, (c) cutting the fed base material sheet using a cutting frame having cutters mounted or formed therein in a structure in which the cutters correspond to rectangular unit pieces to be manufactured, the cutters being arranged such that the shapes of opposite side ends of the cutters coincide with each other when the cutters are successively arranged, the cutting being carried out while the base material sheet is partially overlapped such that a length ('pitch') for a one-time cutting process is equal to a spacing distance between the opposite side ends of the cutters in the longitudinal direction are equal to each other at arbitrary heights of the cutting frame, (d) winding a scrap, produced after the cutting of the rectangular unit pieces, on another roll, and (e) transferring the cut rectangular unit pieces.