Disclosed is an LM guide assembling method using half division, and a computer readable recording medium having a program for executing the same. The method includes: disposing an LM rail on a base; fastening a first hole and a (2n+1)-th hole; installing an angle measuring device; fastening a (2n-1+1)-th hole at step S130; respectively disposing the LM blocks on the first hole and the (2n-1+1)-th hole; disposing the auxiliary shelf on the LM blocks; setting an angle of the auxiliary shelf to a zero angle; moving the two LM blocks to be on a (2n-1+1)-th hole and a (2n+1)-th hole, and measuring an angle of the auxiliary shelf; calculating a straightness correction amount; and moving a position of the (2n-1+1)-th hole by the straightness correction amount, and fastening the hole, wherein, the steps are repeated until n becomes 1.