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.