Kaizen has long been known as an improvement philosophy that starts with small frequent changes to make larger changes in production. These changes come from the ideas and creative thinking of employees to ensure that the production conditions and processes are continuously improved. However, Kaizen not only helps motivate employees to think creatively with effective methods and skills, but it also helps them develop their capabilities, personality, and good work habits. The purpose of this paper is to show a new approach to human resources quality improvement through the Kaizen philosophy as a sustainable and active strategy to improve work performance. With analytical research on the relationship between Kaizen implementation, human resources quality improvement, and production efficiency and exploratory research on particular cases in manufacturing enterprises in Vietnam, the authors point out changes in production efficiency and human capacity before and after implementing improvement (Kaizen) projects. The paper finds significant changes of employee capability (Kaizen practitioners) after evaluating the human resource development process on the basis of six indicators of two groups (namely capacity development, personality development) and a set of criteria using a 5-point scale. In addition, the paper proposes a PDCA based framework with 12 contents corresponding to stages of the human resource development. This paper extends theories related to Lean Manufacturing or Kaizen, highlighting how philosophy of Kaizen has hard and soft impacts on the improvement of performance and human resources.