Abstract: A pipe clamping device having a stronger gripping force by an elastic deform of a clamp ring during screw-tightening is provided. The pipe clamping device includes at least one clamp ring installed between a female bracket and a male bracket, and made of an elastic material to have a predetermined deform, pressure rings installed in the upper and lower portions of the clamp ring, respectively, and an O-ring formed between the pressure ring and the female bracket and pressurizes the pressure rings to closely contact and seal the pipe. Accordingly a pipe can be easily inserted into and assembled with the clamp ring during an assembly. After assembly, when the female bracket is screw-tightened with the male bracket, the entrance of the blade is narrowed and thus the inner diameter of the clamp ring is also narrowed.