Although CD1d‐restricted NKT cells have been implicated as a participant in the regulatory mechanism of autoimmune diseases, it remains unclear how they would regulate human autoimmune diseases such as multiple sclerosis (MS). Furthermore, although the NKT cells comprise CD4⁺ and CD4^– populations, prior studies have often represented them as simply a CD4^– population. Given that CD4⁺ and CD4^– NKT cells may represent functionally distinct populations, it appears crucial to examine the individual NKT subset in autoimmune diseases. Here we studied the frequency and cytokine phenotypes of the CD4⁺ and CD4^– NKT cells in fresh peripheral blood mononuclear cells, and of α‐galactosylceramide‐stimulated short‐term cell lines obtained during the remission or relapse phase of MS as compared with from healthy subjects (HS). Here we report that CD4⁺ NKT line cells expanded from MS in remission (MS‐rem) would produce a larger amount of IL‐4 than those from HS or from MS in relapse (MS‐rel). They were significantly biased for T_h2 as judged by the IL‐4/IFN‐γ balance. However, there was no functional bias toward T_h1 or T_h2 in CD4^– NKT line cells from MS‐rem due to the defects in both IFN‐γ and IL‐4 production, compared with HS. Of note, although double‐negative NKT cells in the periphery were greatly reduced, the reduction of CD4⁺ NKT cells was only marginal, if any, in MS‐rem compared with HS. The T_h2 bias of CD4⁺ NKT line cells from MS‐rem may support an immunoregulatory role for the CD4⁺ NKT cells in vivo.