A 3D printing method using a photocurable ink composition which exists as liquid at a predetermined phase-change temperature or higher, but hardens to a solid matter at a low temperature equal to or lower than the phase-change temperature, the 3D printing method comprising: installing a build platform on one side of the top of a conveyor belt which is driven in one direction through a pulley, such that the build platform is inclined at a predetermined angle with the top surface of the conveyor belt; applying a photocurable ink composition layer by layer onto the top surface of the inclined build platform; selectively curing the applied photocurable ink composition layer by emitting a light pattern onto the ink composition layer through a light emitting unit, producing a 3D printed matter through printed matter layers which are repeatedly stacked in a direction indicated at the predetermined angle with the top surface of the conveyor belt, by repeated performing the steps of applying the photocurable ink composition layer by layer onto the ink composition layer onto which the light pattern has been completely emitted, and selectively curing the applied photocurable ink composition layer by emitting the light pattern onto the ink composition layer through the light emitting unit, wherein the curing process through the application of the ink composition and the light emission is performed in a low temperature chamber which is maintained at a low temperature equal to or lower than the phase change temperature of the ink composition, the conveyor belt is driven in the one direction according to the progress speed of the printing process, and transfers a printed matter block stacked thereon in the one direction, and a printing space for a subsequent layer is continuously secured by the transfer of the printed matter block through the conveyor belt. installing a build platform on one side of the top of a conveyor belt which is driven in one direction through a pulley, such that the build platform is inclined at a predetermined angle with the top surface of the conveyor belt; applying a photocurable ink composition layer by layer onto the top surface of the inclined build platform; selectively curing the applied photocurable ink composition layer by emitting a light pattern onto the ink composition layer through a light emitting unit, producing a 3D printed matter through printed matter layers which are repeatedly stacked in a direction indicated at the predetermined angle with the top surface of the conveyor belt, by repeated performing the steps of applying the photocurable ink composition layer by layer onto the ink composition layer onto which the light pattern has been completely emitted, and selectively curing the applied photocurable ink composition layer by emitting the light pattern onto the ink composition layer through the light emitting unit, wherein the curing process through the application of the ink composition and the light emission is performed in a low temperature chamber which is maintained at a low temperature equal to or lower than the phase change temperature of the ink composition, the conveyor belt is driven in the one direction according to the progress speed of the printing process, and transfers a printed matter block stacked thereon in the one direction, and a printing space for a subsequent layer is continuously secured by the transfer of the printed matter block through the conveyor belt.