In ubiquitous computing environment, identification of objects and places in the real world is important, and 2-D printing code is useful to store identifiers of them. However, since it is easy to modify the content stored in the 2-D code, we must verify whether the identifier written in the 2-D code is indeed issued by the authorized organization. In this paper, we propose a verification method for identifiers stored in the 2-D code. Our system makes sure that the identifier is indeed issued by the authorized organization, and the size of pair of identifier and its authenticator is small enough to be written in a 2-D code. Furthermore, the proposed system has compatibility with the existing 2-D code reading software. Our system is now operated in practical use, and some services based on this mechanism have been developed.