Provided are an iPS cell derived from a somatic cell such as an NKT cell, having the α-chain region of the T cell antigen receptor gene rearranged to uniform Vα-Jα in an NKT cell receptor-specific way, NKT cells differentiated from the iPS cell, a method of creating the same, and an immune cell therapy agent prepared using cells differentiated from the iPS cell. Also provided are an iPS cell having TCRα rearranged to NKT-TCR (NKT-iPS cell), obtained by contacting a somatic cell, such as an NKT cell, having the α-chain region of the T cell antigen receptor gene rearranged to uniform Vα-Jα in an NKT cell receptor-specific way, with nuclear reprogramming factors, isolated NKT cells obtained by differentiating the iPS cell ex vivo (iPS-NKT cell), a method of generating CD4/CD8-double positive NKT cells (DP-NKT cells) and mature NKT cells from NKT-iPS cells by altering the combination of feeder cells and/or cytokines, a method of expanding the iPS-NKT cells, and an NKT cell cytotherapy agent comprising NKT cells activated with α-galactosyl ceramide (α-GalCer), or iPS-NKT cells, and α-GalCer in combination.