A compound represented by the formula
wherein R
1
, R
2
, R
3
and R
6
are the same or different and each is a hydrogen atom or a substituent; one of R
4
and R
5
is a hydrogen atom and the other is a group represented by the formula: —C(═X)—R
7
wherein X is N—O—R
8
or N—NH—R
9
wherein R
8
and R
9
are the same or different and each is a hydrogen atom or a group bonded via a carbon atom; and R
7
is a hydrogen atom or a substituent, and the like and a salt thereof have a superior IκB kinase inhibitory activity, and useful as pharmaceutical agents such as agents for preventing or treating diabetes and the like.