An agent for suppressing the production of various cytokines (IL-8 and the like) and inflammatory mediators, an agent for suppressing the expression of COX-II and the like, or an inhibitor of various phosphorylation enzymes (ATF2 and the like), which contains a TLR signaling inhibitory substance, preferably a compound represented by the formula (I) or the formula (II)wherein each symbol is as defined in the specification, or a salt thereof or a prodrug thereof.
