The purpose of the present invention is to provide a novel compound having a selective JAK3-inhibiting effect and excellent oral absorption. Moreover, the purpose of the present invention is to provide a medical drug useful, on the basis of a JAK3-inhibiting effect, for the prevention and/or treatment of JAK3-associated disease, particularly rheumatoid arthritis or multiple sclerosis. Provided is an azaindole derivative, or a salt thereof, having a cycloalkenyl group that is represented by formula (I) [where R