This study analyzes the installation process of the elevator of a case company in Thailand by using an expert review method, which identifies failure modes and their associated effects and possible causes of the installation process. The qualified experts assign the severity, occurrence, and detection ranking to each failure mode to get the risk priority number. After that, the Pareto principle is used to discover the few critical failure modes for developing the remedy action plan. The result of this study determines the actions for the elevator installation process to perform corrective actions which can prevent the failure modes from happening, minimize the waste, and reduce the unreliability.