Abstract: According to the invention, a rotary cutter is provided, which includes a fixed blade having a straight cutting edge and a rotary blade having a spiral cutting edge. The rotary blade is installed for rotation about an axis extending parallel to the cutting edge of the fixed blade, the spiral cutting edge of the rotary blade moving along a path which extends tangentially to said cutting edge of the fixed blade. At least one of the fixed blade and the rotary blade is shorter than the width of a paper strip. Accordingly, the rotary blade and the fixed blade cooperate with each other to partially cut the paper strip widthwise while leaving the opposite end portions uncut. The fixed blade has opposite surfaces extending toward the cutting edge thereof, one of which comprises an inclined surface formed on the paper inlet side of the fixed blade and disposed at an angle less than 60.degree. with respect to the paper strip.