A gene transfer efficiency enhancer of the present invention which contains a histone deacetylase inhibitor ) as an active ingredient is capable of enhancing gene transfer efficiency in a gene transfer mediated by an adeno-associated virus vector while retaining the advantages of the adeno-associated virus vector. The uretonimine-modified isocyanate composition comprises a polyisocyanate composition having two or more isocyanate groups and comprising 4,4\u2032-diphenylmethane diisocyanate and a catalyst for catalyzing a reaction of the isocyanate groups to form carbodiimides available for forming uretonimines and uretonimine oligomers. The well region has a step defining a higher portion and a lower portion lower than the higher portion so that the impurity diffused region for guard ring is located at the lower portion. The stabilizer is a urea of an aromatic amine. In general, automatic memberships to social networks, social groups and to discussion lists are provided to users, based on user’s current location.