An immunotherapeutic agent comprising a heterocyclic compound represented by the following general formula (I) or a metabolite thereof, or a pharmaceutically acceptable salt thereof as an active ingredient. Embedded image下記一般式(I)で示される複素環式化合物もしくはその代謝物、又はその薬学的に許容される塩を有効成分とする免疫療法剤。【化1】