The present invention relates to a composition for preventing and treating inflammatory diseases and immune diseases, containing a Sargassum muticum extract and apo-9′-fucoxanthinone as active ingredients. According to the present invention, the Sargassum muticum extract and apo-9′-fucoxanthinone show an excellent inhibiting activity for the generation of IL-12, IL-6 and TNF-α, which are inflammatory cytokines, in a macrophage and a dendritic cell due to a stimulating factor causing an inflammatory response, remarkably inhibit MAPK and AP-1 activity, and inhibit the activity of NLRP3 inflammasome which is known to be involved in the pathogenesis of various immune inflammatory diseases, and thus can be ultimately useful for the development of an agent for treating inflammatory diseases and immune diseases caused by an excessive immune inflammatory response. In addition, according to the present invention, the Sargassum muticum extract and apo-9′-fucoxanthinone are derived from an edible natural product and do not cause cytotoxicity so as to be safe in vivo, and thus can also be safely used as a material for medical supplies and a dietary supplement.
