Few studies have examined the individual and social impact of smoking behavior in the Japanese population. The purpose of this study was to clarify the association between smoking behavior and socio-demographic factors, lifestyle, mental health and work characteristics of Japanese civil servants. A self-administered questionnaire survey of 1,439 employees (821 men and 618 women) aged 20-64 yr was conducted in a local government department in 2001. The questionnaire included items on socio-demographic factors, education level, grade of employment, lifestyle, affect balance scale, and work characteristics. Smoking status was divided into current smoker, ex-smoker and never smoked. Multiple logistic regression analysis was performed to evaluate the relationship between smoking and the other items. Men presented a higher smoking prevalence rate than women (53.1% vs. 4.9%). In men, a strong relationship between current smoker and advanced age (40 yr or older), low education level, less physical activity, irregular breakfast and negative affect balance was found. Among men with a low education, the prevalence of smoking cessation was significantly lower in comparison to men with a high education. In women, being young (20-29 yr), unmarried (single or other), having a hobby, and irregular breakfast were associated with smoking behavior. Furthermore, smoking cessation was significantly associated with having a hobby and negative affect balance. The above results suggest that socio-demographic, lifestyle and mental health characteristics are independently associated with current smoking. These factors should be considered in smoking cessation policies as program components.