This paper discusses factors for sustainable working style that help workers remain healthy and motivated, with work engagement as a key concept, based on scientific findings. In the second section, I outline occupational health psychology as a scientific basis of work engagement and introduce activities in this field in Japan and other countries. In the third section, I refer to the concept and measurement of work engagement and major empirical findings on it. In the fourth section, I refer to sustainable working style, whereby I focus on improving work engagement and on facilitating off-job experience such as work-life balance and leisure time. In the fifth section, I mention the collaboration between occupational health psychology and economics/business science to facilitate sustainable working style, followed by a summary and future directions in the final section.