Introduction Integration of Occupational Health and Safety(OHS) and Workplace Health Promotion(WHP) aiming at employees’ health and well-being attracts attention in WHO’s ‘Healthy Workplace Framework’ and NIOSH’s ‘Total Worker Health’. Also in Japan, WHP is actively conducted in many companies in trends, however there are few studies on the effectiveness of WHP in Japan. We examined the impact on its lifestyle and health literacy and success factors from the practical experience of WHP in a company.

Methods We reported OHS and WHP activities in an architectural consultant company for 15 years, and its impact in the pre-post comparison design to study its success factors.

Results OHS and WHP activities at the company began in 2001. It inducted occupational physician (OP)/OHS committee (2001); employment of occupational health nurse (OHN)/developed guidelines (2002); e-mail newsletters (2003); first health survey (2005), full-time employment of OHN(2006), healthy lunch box project (2007), OHSMS (2009); health policy (2011); health lecture/portal web-site (2012); mental health training/company sports festival (2013); health lecture by labour union(2014); gymnastics with the president/3rd health survey (2015), delivery of health lecture to each department (2016), etc. In the pre-post comparison of lifestyles using health survey, employees thinking nutrition balance (40→79%), having exercise habits (31→36%) and sufficient sleep (12→18%) increased, improving the employee’s health literacy for four consecutive years from 2014 to 2017.

Conclusion A good impact on lifestyle and health literacy was obtained from 15 years of WHP. It was considered that success factors of WHP practice involving human resources including management/labour union are:

1. discovery of key persons highly interested in health,

2. existence of OHN,

3. corporate culture with good communication, and

4. clear management’s commitment and health policy.

WHP will be increasingly important in Japan as ageing population and health disparities progress. Its important outcome is organisational and employee health literacy, so we want to continue the research to contribute to its improvement.