Neudesin was identified as a secretory factor expressed in the nervous system. On the other hand, neudesin is expressed in various organs and cells, suggesting that it plays roles in tissues other than neural tissues. We found that neudesin was expressed in dendritic cells (DCs) in the mouse spleen, which play a crucial role in the initiation of adaptive immune responses. Therefore, considering the possibility that neudesin may affect the acquired immune response, we first investigated whether neudesin has an effect on DCs using bone marrow-derived dendritic cells (BMDCs). Neudesin expression levels increased during the differentiation of bone marrow cells to BMDCs, and its expression level in BMDCs was reduced by lipopolysaccharide (LPS) treatment. BMDCs from neudesin knockout mice showed increased production of various cytokines, such as IL-12p70 and TNF-α, under LPS-stimulated conditions, compared with BMDCs from wild-type mice. In addition, treatment with recombinant neudesin suppressed the expression of cytokine genes in LPS-stimulated BMDCs from neudesin knockout mice. T cell proliferation was more strongly induced by co-culture with BMDCs from neudesin knockout mice than by those from wild-type mice. BMDCs from neudesin knockout mice showed increased lactate production, glucose consumption, and expression levels of glycolysis-related factors, suggesting that neudesin inhibits glycolysis, which promotes DC activation. The increased cytokine production in BMDCs from neudesin knockout mice was suppressed by the glycolytic inhibitor, 2-deoxyglucose. These results suggested that neudesin is a novel suppressor of DC function through the inhibition of glycolysis.