The present invention relates to a composition for preventing or treating asthma comprising a Pistacia weinmannifolia J. Poiss. ex Franch extract or a fraction thereof. The Pistacia weinmannifolia J. Poiss. ex Franch extract or the fraction thereof according to the present invention does not exhibit toxicity, inhibits the generation of NO, IL-4, IL-5, and IL-13 and the generation of reactive oxygen species in the bronchial tubes, and has significantly induced the alleviation of airway hyperresponsiveness, inhibition of the infiltration of inflammatory cells into the bronchial tubes, and reduction of inflammatory cells in bronchoalveolar lavage fluid in an ovalbumin-induced asthma mouse model. In addition, the Pistacia weinmannifolia J. Poiss. ex Franch extract or the fraction thereof according to the present invention effectively inhibits the secretion of immunoglobulins in serum, secretion of mucus in the bronchial tubes, and infiltration of inflammatory cells into lung tissue and thus can be usefully used as a safe preparation for preventing and treating asthma.