In this paper, an information model is proposed for the life-cycle cost data management of cable-stayed bridges. Firstly, a unit cost model for all cost data throughout bridge lifetime is proposed in an attempt to detailedly represent various cost elements in a general expression. Each cost element has a dollar value which could be detenriinistic, probabilistic, or fuzzy. Then, an information model based on ISO/STEP standard is developed for the integrated cost data management of highway bridges. The cost information is categorized into initial cost, operation and maintenance cost, decommission cost, and others. Finally, the developed information model is applied to the Seohae Grand Bridge, which is currently the longest cable-stayed bridge in South Korea, to illustrate its applicability and efficiency. The model can be an integral part of an interoperable bridge project information system because it is international standard based. Future works for the study are given in the conclusion.