A pipe coupling device includes a body part, fastening parts, and pressurizing parts. The body part has a multi-stepped insertion hole penetrating the central portion thereof, a stepped latching portion formed on the inner circumference of the insertion hole, and first projections continuously formed on the upper surfaces of the externally threaded portions. Each of the fastening parts has an internally threaded portion formed on the inner circumference thereof and is screwed onto the externally threaded portion, a coupling hole penetrating the central portion thereof so as to be in communication with the insertion hole, a first inclined plane formed around the boundary between the internally threaded portion and the insertion hole. Each of the pressurizing parts has a stepped foot portion formed on the outer circumference of one side thereof.