The actual cost of a construction project is composed of not only production costs, but also transaction costs. The presented model includes the uncertainty of the owner’s behavior, the uncertainty of the contractor’s behavior, the uncertainty in the transaction environment and mechanism, and project management efficiency, to illustrate the influence path of the transaction costs borne by the owner. The model is tested by the structural equation modeling (SEM) using the data collected from construction project owners. The finding indicate that uncertainty in the transaction environment and mechanism appears to be the core construct of the model due to its strong linkages with transaction costs and the owner’s behavior, the contractor’s behavior, and project management efficiency. The uncertainty of the contractor’s behavior is also found to affect project management efficiency positively. A certainty behavior on the part of the owner reduces the uncertainty in the transaction environment and mechanism, increases the efficiency of project management, and reduces the transaction costs of construction project.