Smoking is the riskiest factor for impairment of pulmonary function. Recent researches have indicated that abdominal obesity is also associated with the impairment. 'Lung age' is a novel index to evaluate respiratory function, and it is calculated from the data of the height, sex, and forced expiratory volume in 1-second. Using 'lung age' as an index, we studied on the relationship of 'lung age' to smoking, waist circumference, BMI, or metabolic syndrome. The study population included 1,681 persons who visited our Medical Checkup Office, and the population consisted of smoker group (n = 279) and non-smoker group (n = 1,402). In both men and women, 'lung age' was significantly higher in the smoker group than in non-smoker group (p < 0.05). In addition, the smoker group and non-smoker group were classified by waist circumference, BMI, and the presence of metabolic syndrome, respectively. As a result, 'lung age' of smoker with abdominal obesity group, smoker with obesity group, and smoker with metabolic syndrome group were significantly high. Furthermore, in multivariate linear regression analysis, we examined relation between 'lung age' and the following factors including gender, smoking, waist circumference, BMI and metabolic syndrome. There was closely related to 'lung age' in order of gender, smoking, metabolic syndrome, and waist circumference. Both smoking and abdominal obesity should be significant risk factors in increasing 'lung age'.