By searching various compounds having an inhibiting activity against IL-12/IL-23 production, the present invention provides a pharmaceutical composition or a therapeutic or preventive agent for diseases related to IL-12/IL-23 excessive production each of which comprises the compound(s) of the present invention.More specifically, the present invention provides an imidazopyridazine compound having an inhibiting activity against IL-12/IL-23 production or pharmaceutically acceptable salts thereof； and a useful pharmaceutical composition or a useful therapeutic or preventive agent for diseases related to IL-12/IL-23 excessive production each of which comprises said compound or pharmaceutically acceptable salts thereof.
