A discoid lower blade and a discoid upper blade, having a sharper knife angle compared with that of the lower blade, are arranged such that rotational axes thereof are parallel to each other, and portions of the blades overlap one another in the direction that the rotational axes extend. A sheet with a coating layer on one side is fed through and shear-cut between the upper and lower blades in the direction perpendicular to the rotational axes, with the surface of the sheet opposite the coating layer in contact with a periphery of the lower blade while the blades are rotated. When the sheet is shear-cut, a contact start position, where contact between the sheet and the upper blade starts, is positioned upstream in the feed direction of the sheet but outside a contacting area of the sheet, where the sheet contacts the periphery of the lower cutting blade.