Provided is a novel compound, which selectively and strongly inhibits JAK3, has an excellent effect of inhibiting the proliferation of human peripheral blood monocytes and a high oral absorbability and shows an activity of inhibiting IL-2-induced IFN-? production in vivo, or a salt thereof and a medicinal composition comprising the same. A compound represented by formula (I) [wherein: X represents -CH=CH-, -NH-, a sulfur atom or an oxygen atom; and n is an integer of 0-2] or a salt thereof.