Granted by research project of Japan Society for the Promotion of Science (JSPS), this research provides planning of installing Wind Power Turbine (WPT) in an existing Local Weak Power System (LWPS). Wind power generation is expected to be used as a power reserve to improve the reliability degree and reduce line loss of LWPS, that suffers from critical load in each summer. Installation buses are selected based on the existing reliability degree derived from system condition in energy service and load demand, two reliability indices namely Weakness Degree in Energy Supply (WDES) that represents bus energy supply ability in a short critical time and Reliability Index in Energy Supply (RIES) that represents bus average energy supply ability during annual time are applied. Appropriate type of WPT is selected according to Percentage Rate of Availability Index (PRAI) and Percentage Rate of Utilization Index (PRUI) derived from Monthly Average Wind Speed (MAWS) through the target region. Operational reliability and stability are analyzed based on formed system characteristics after introducing WPT.