This paper discusses WBS (Work Breakdown Structure) that is known for technique of basic project management. The WBS use in domestic industries often exhibit errors in Its structure. The most common serious error is space-oriented breakdown structure of PBS (Product Breakdown Structure) that becomes the core element of the WBS. This paper proposes a method to correct the problem of space-oriented breakdown structure constructed in domestic railroad industry. DSM method was adopted to construct PBS containing function-oriented structure. The proposed process and method will contribute to minimize time that take to construct an accurate and useful PBS.