The present invention relates to: a composition for reprogramming somatic cells into induced pluripotent stem cells, the composition containing a Reptin protein or a gene encoding the same; and a method for reprogramming somatic cells into induced pluripotent stem cells by using the composition. According to the present invention, somatic cells can be effectively reprogrammed into induced pluripotent stem cells without using a c-myc gene and the like which are known to be able to induce tumors through the overexpression of Reptin. In addition, induced pluripotent stem cells prepared by using Reptin can be differentiated into various cells such as cardiomyocytes, insulin-producing cells and nerve cells due to having excellent pluripotency or potency, and thus can be applied, as a cell therapeutic agent for treating various diseases, to stem cell transplantation treatment and the like.