To produce and/or maintain naïve pluripotent stem cells capable of highly expressing genes important for maintaining an undifferentiated state, which could not be achieved by known methods for producing pluripotent stem cells. The present invention can produce naïve pluripotent stem cells capable of maintaining an undifferentiated state by introducing and allowing transient expression of six genes (Oct3/4, Klf4, c-Myc, Sox2, Nanog, and Klf2) among the so-called initializing factors, and further performing culturing in a medium containing LIF, an MEK inhibitor, a GSK3 inhibitor, a cAMP production promoter, a TGF-β inhibitor and a PKC inhibitor. Thus, the problem of the present invention can be solved.