FRBR(Functional Requirements for Bibliographic Records) provides a structured conceptual model for relating the data which are recorded in bibliographic records to identify information resources. FRBR has 4 bibliographic entities - the work, expression, manifestation, and item - in its conceptual model.In this paper, the difference in the 'work' conception between FRBR and international standard numbers is examined. Consequently, the following points are observed:(1) The ISBN, ISSN, and ISMN identify manifestation level, as they refer to the physical expression of a work. The IARN, ISRC, and ISAN identify expression level, irrespective of its manifestation. The ISWC and ISTC identify work level - the unique artistic creation, whatever its expression or manifestation is. (2) ISWC and ISTC does not use the word 'work' in the same way as FRBR does. I think that the differences in meanings of the two usages 'work' come from the different positions to information resources.