The target is to provide PDE IV inhibitors which have a highly potent anti-asthmatic and/or COPD-prophylactic/therapeutic profile with unexpectedly excellent safety. A compound of the formula (1): wherein A is phenyl, pyridyl, 1-oxypyridyl, or thienyl, which may be unsubstituted or optionally substituted with one or more members selected from the group consisting of hydroxyl, halogen, cyano, nitro, lower alkyl, lower alkoxy, lower alkylcarbonyloxy, amino, carboxyl, lower alkoxycarbonyl, carboxy-lower alkylene, lower alkoxycarbonyl-lower alkylene, lower alkylsulfonyl, lower alkylsulfonylamino, and ureido; R.sup.1 is a group selected from the group consisting of hydrogen, hydroxyl, halogen, cyano, nitro, lower alkoxy, amino, carboxyl, and lower alkoxycarbonyl; R.sup.2 is hydrogen or lower alkyl; and m is an integer of 1 to 3; or a pharmaceutically acceptable salt thereof, possesses highly excellent PDE IV-specific inhibitory actions and is useful as an anti-asthmatic drug and/or a prophylactic/therapeutic drug for COPD with high safety.