Disclosed is a pharmaceutical composition for the prophylaxis and therapy of inflammatory diseases, allergic diseases, or asthma, comprising a velvet apple (Diospyros blancoi A. DC.) extract as an active ingredient. Having the inhibitory activity against the nuclear translocation of NF-κB, whose level is rapidly elevated in response to inflammatory stimuli, the velvet apple extract can suppress the production of NO and PGE2, the expression of iNOS and COX-2, and the release of IL-1β and TNF-α, and can significantly down regulate Th2-mediated IL-4 and IL-13 production. In addition, the extract was found to inhibit the activation of eosinophils in bronchoalveolar lavage fluid, and to suppress the secretion of immunoglobulins and chemokines in bronchoalveolar lavage fluid and blood, as measured by in vivo tests on an ovalbumin-induced asthma mouse model. Therefore, the extract can be used in the method for preventing or treating various inflammatory disorders, allergic diseases, or asthma.