A coupling assembly for connecting pipes includes two or more couplers which are arranged facing each other in order to connect pipes continuously disposed in the axial direction, and the pipes are connected to each other in a state in which coupling members are temporarily assembled to the plurality of couplers. The couplers have catch parts which are inserted into coupling grooves formed in the pipes and have inner diameters corresponding to the outer diameters of the coupling grooves. Interference preventing grooves are formed in both sides of the catch parts and prevent interference between the pipes and the catch parts to allow the outer circumferential surfaces of the pipes to pass through between the temporarily assembled couplers.