Abstract: The present invention relates to a composition comprising a repressor of mitofusin gene expression, an inhibitor of mitofusin protein activity, or a mixture thereof as an active ingredient for promoting reprogramming a differentiated cell into a pluripotent stem cell, and a use thereof. The composition according to the present invention increases the efficiency of reprogramming as well as reduces the time required for reprogramming to produce pluripotent stem cells. Therefore, the present composition can be beneficially used to develop the production technology of high efficiency pluripotent stem cell and secure a large-scale culture system. Further, the present composition can be beneficially used to maintain pluripotent stem cells and screen the compounds capable of promoting the reprogramming into pluripotent stem cells.