An anti-expansion and anti-seismic pipe fitting. The pipe fitting includes a body into which end portions of plural pipes are inserted. The body has a receiving jaw formed on the inner circumferential surface of an end portion, into which each of the pipe is inserted such that an inner diameter of the body is enlarged. A packing is arranged on the receiving jaw. A cap is coupled to the end portion of the body such that the packing and the pressurizing member are mounted inside the cap. Buffering means are included for absorbing expansion and contraction of the pipe. The pipe fitting can absorb deformation due to the expansion or contraction of the pipes. Moreover, because all of the pipes and the pipe fitting have the same inner diameter, the fluid flowing inside the pipes maintains uniform pressure, and hence, the fluid can flow smoothly inside the pipes.