This study investigates reference books held in (1) Japanese libraries with a high number of reference transactions and (2) libraries that consider reference services as important. The results show that the Encyclopedia of Modern Japanese Literature and the Encyclopedia of Japanese People were held in these types of libraries or municipalities. The Encyclopedia of News in the Meiji Era and the Techno Atlas of Japan were popular at relatively small municipality libraries, such as those in cities, towns, and villages, whereas the Series of Pandect of Modern Japanese Literary was popular in large municipality libraries, such as those in prefectures and special wards.