Abstract: A paper clip made of a resilient steel wire bent into shape, which comprises two front bends disposed at same plane and formed into a clamping portion for holding sheets of paper inserted therebetween, and an unitary wave-like back bend substantially perpendicular to the two front bends and forming a stop portion for stopping the paper which is fastened in the clamping portion. The wave-like back bend is formed of at least one peak and one wave trough so as to provide stronger tensile elasticity permitting the clamping portion to tightly retain more sheets of paper.