This invention relates to a phosphodiesterase IV inhibitor containing as an active ingredient a pyridylacrylamide derivative represented by the following formula (I): (wherein Ar1 represents substituted or unsubstituted pyridyl; Ar2 represents phenyl substituted by alkoxy, etc.; R1 represents hydrogen, alkyl, or aryl; R2 represents hydrogen, alkyl, cyano, or alkoxycarbonyl; R3 represents hydrogen or optionally substituted alkyl; X represents oxygen or sulfur; A and B are the same or different and each independently represents hydrogen, hydroxyl, alkoxy, or alkylthio, or A and B together represent oxo, thioxo, etc., or A may be hydroxyl and B may be 1-alkylimidazol-2-yl; and n is an integer from 1 to 3) or a pharmaceutically acceptable salt thereof.