This study identifies influential factors for invigorating the public management office (PMO) system for system integration (SI) projects in public sectors and analyzes the priority of each factor from the point of different stakeholders, i.e., owners, SI company, and PMO. Based on the literature review, four first-level influential factors are identified: legal system maintenance, owner’s capability, SI company’s capability, and PMO’s capability. Among them, the PMO’s capability is determined as the most critical factor by all the stakeholders. Among the second-level influential factors, the capabilities of professional engineers and project managers are considered as important among the PMO’s capability, whereas the reasonable consulting fee is considered as the most critical factor among the legal system maintenance. With respect to each stakeholder, project management capability is considered as the most important factor for owners, while the reasonable consulting fee is considered as the most important factor for PMO.