A novel immunosuppressive agent, more specifically an immunosuppressive agentcomprising, as an active ingredient, a heterocyclic compound represented bythe generalformula (I) (wherein X or other variables are as defined in the specification)or apharmaceutically acceptable salt thereof； a novel heterocyclic compoundrepresented bythe general formula (II) (wherein X or other variables are as defined in thespecification)or a pharmaceutically acceptable salt thereof； and use of the compound or saltas anantitumor agent.
