The present invention relates to an extract isolated from Sophorae Radix useful for prevention and treatment of respiratory diseases. More specifically, the present invention relates to a pharmaceutical drug comprising the Sophorae Radix extract having excellent effects of inhibiting airway contraction, respiratory infections, 5-lipoxygenase activity, phosphodiesterase 4 activity, airway hyper-responsiveness and airway remodeling; antagonistic activity against leukotriene D4; and an antitussive effect, thus being useful for prevention and treatment of respiratory diseases such as asthma, acute or chronic bronchitis, allergic rhinitis, acute upper respiratory infections and acute lower respiratory infections, and the like.