Environmental tobacco smoke (ETS) contains a large variety of substances, of which at least 50 are known to or are believed to be carcinogenic. Although the Ministry of Health and Welfare has started to prevent public exposure to ETS by enacting indoor smoking bans, some facilities still allow their customers or users to smoke indoors. In this study, indoor air quality in a pub was investigated by monitoring particulate matters (PM1.0 and PM2.5), heavy metals (As, Cd, Cr, Pb) and nicotine concentration to figure out the influence force of smoking behavior on indoor air quality. Smoking behaviors are revealed to be a major contributor the contamination of indoor air in pubs. The range of PM2.5 mass concentrations were 82.2~208.0 μg/m3 and the mean concentration of PM2.5 was 135.9 μg/m3. In the case of nicotine, the mean concentration was 12.2 μg/m3 with a range from 2.7 to 24.1 μg/m3. In the results of metal analysis, the levels of heavy metals in particulate matters in a pub were found to be much higher than those of the other public facilities.