The purpose of this paper is to describe a proposed support system of Kaizen activity which contributes to improve related performance indicators in a production department. Background research consisted of the following three parts. First, a Decision Support System (DSS) provided an illustration for the proposed system; its three elements of interest include Kaizen case-base, Model-base and User-interface. The first element accumulates useful cases for developing new cases. The second element accumulates models to utilize the case-base effectively, including the Kaizen strategic model, Kaizen objective model, Kaizen data analysis model, and model building blocks and subroutines. The third element links Kaizen case-base, Model-base and Kaizen engineers. The linkages are realized by four procedures: installation of proposed support system, construction of Kaizen case-base, evaluation of the case-base, and development of new cases. The second portion of our research was a discussion of Kaizen case-base from three viewpoints: its utilization purpose, its information structure, and data types accumulated in it. Thirdly, investigation of the three primary model types mentioned above was performed and the proposed model-base was constructed. Proposed system was designed to maintain and improve Key Performance Indicators (KPIs) in a manufacturing system through discussions with Kaizen experts whose factory collaborated in this research.