The present invention relates to a composition for preventing or treating asthma, having, an active ingredient, a saturated or unsaturated fatty acid having 12 to 22 carbon atoms. The saturated or unsaturated fatty acid functions to inhibit or eliminate various asthma symptoms induced by ovalbumin. Specifically, the fatty acid inhibits the proliferation of leukocytes, neutrophils, lymphocytes and monocytes in BALF and serum, inhibits the proliferation of bronchial epithelial cells, reduces mucus in bronchioles, and reduces infiltration of inflammatory cells around bronchioles and blood vessels in a dose-dependent manner. Also, the fatty acid induces a decrease in the expression of IFN-γ, IL-12p40, IL-4, IL-5, IL-13 and TNF-α, which are Th2 cell-related cytokines. Therefore, the fatty acid overcomes the side effects of current asthma therapeutic agents, has an excellent therapeutic effect without having toxicity, and may advantageously be used as a composition for preventing, treating or alleviating asthma.
