: We have developed a “WBS(Work Breakdown Structure) process model” for a business application software development project. We have also developed a project management system called “PRO-NAVI” which works on the “WBS process model.” This WBS process model” provides (1) mutual mapping to the “software development processes”, “activities”, “products”, “know-how,” “rules”, and “standards”, and provides (2) comprehensive control. The role of “project management” in a business application software development project is recognized to be of more importance. These projects generally involve huge efforts, and cost heavy pay-loads to their “project management.” Thus, an efficient project management system is needed. We have developed “PRO-NAVI”. We have applied and evaluated “PRO-NAVI” with number of projects and confirmed, it is effective for efficient project fulfillment.