A boring method using a horizontal boring apparatus having a direction control function includes: a first boring step of performing a boring work in a horizontal direction using a rod coupled to a driving shaft of a head part moving along a leader installed in a body of a boring machine and a core drill installed on the rod; a sampling step of collecting sample cores in a region where a sample core collection work is required when performing a boring work in the first boring step; a grouting step of performing a grouting work by injecting mortar into a boring region requiring a direction change after the sampling core collection work has been finished together with the boring work in the first boring step; a boring direction changing step of performing the boring work while changing a boring direction at a predetermined angle from the boring direction in the first boring step by mounting a mud motor, which changes a forwarding direction of the boring work when boring an end portion of the rod coupled to the head part; and a second boring step of performing a boring work by separating the mud motor from the end portion of the rod and mounting a core drill to the end portion of the rod for the boring work after the boring direction changing step has been finished.