An object of the present invention is to provide a material capable of further accelerating growth of pluripotent stem cells, such as pluripotent stem cells, without impairing pluripotency thereof. In other words, the invention is an agent for accelerating growth of pluripotent stem cells, containing a β-nicotinamide mononucleotide or a pharmaceutically acceptable salt thereof, and a solvate thereof as an active ingredient; and is a method for culturing pluripotent stem cells, including culturing pluripotent stem cells in a culture medium that contains a β-nicotinamide mononucleotide or a pharmaceutically acceptable salt thereof, and a solvate thereof.