The present invention provides a compound having anexcellent JAK3 inhibition activity and being useful as anactive ingredient of an agent for treating and/or preventingvarious immune diseases including autoimmune diseases,inflammatory diseases, and allergic diseases.As a result of studies on a novel condensed heterocyclicderivative, the inventors have found that a compound havinga cross-linked structure has an excellent JAK3 inhibitionactivity, and have completed the present invention.In other words, it is verified that the compoundaccording to the present invention has an inhibition activityagainst JAK3 and is thus useful as an active ingredient of anagent for treating or preventing diseases caused byundesirable cytokine signal transmission (e.g., rejectionduring organ/tissue transplantation, autoimmune diseases,multiple sclerosis, rheumatoid arthritis, psoriasis, asthma,atopic dermatitis, Alzheimer's disease, and atheroscleroticdisease), or diseases caused by abnormal cytokine signaltransmission (e.g., cancer and leukemia).
