The present invention provides: a novel use of a specific bicyclic nitrogenated heterocyclic compound as a PDE7 inhibitor； a novel bicyclic nitrogenated heterocyclic compound having a PDE7 inhibition activity, a method for producing the compound, a use of the compound, and a pharmaceutical composition containing the PDE7 inhibitor or the compound； and others. More specifically, the present invention provides a PDE7 inhibitor containing, as an active ingredient, a compound represented by formula (I) [wherein the symbols have the same meanings as those described in the description] or a pharmacologically acceptable salt thereof.
