Abstract: The present invention relates to a pharmaceutical composition for preventing and treating cancer or inflammatory disease, containing an NDRG3 expression or activity inhibitor as an active ingredient. Furthermore, the present invention relates to an NDRG3 protein-specific antibody and a use thereof. Specifically, the antibody to the NDRG3 protein is prepared, and the antibody is used to verify that NDRG3 mediated by lactate generated from a hypoxia reaction promotes cell proliferation, angiogenesis, and cytokine expression through the lactate-NDRG3-c-Raf-ERK signaling pathway, and thus the antibody binding to the epitope of the NDRG3 or a fragment of the antibody can be favorably used in the research of cancer or inflammation occurrence mechanism, the development of novel genes involved in the mechanism, and the development of therapeutic agents and new pharmaceuticals.