Introduction: The use of electronic cigarette (e-cig) is expanding rapidly. However, there has been little research on the relationship between actual smoking habit and blood heavy metal levels of e-cig smokers. Methods: This study used data from sixth (2013- 15) and seventh (2016-17) Korea National Health and Nutritional Examination Surveys. Total 12,192 subjects who had completed smoking behavior survey and measurements of urine cotinine and blood heavy metal level were enrolled in this study. We categorized them into three groups; active e-cig smokers (who smoked e-cig in the last 30 days), conventional cigarette (c-cig) smokers, never smokers. We compared smoking habit, urine cotinine level and blood heavy metal levels among them. Results: Of the 12,192 subjects, 214 (1.8%) were active e-cig smokers, 1,884 (15.5%) were c-cig smokers, 10,094 (82.8%) were never smokers. Average smoking amount (14.08 ± 7.14 vs. 13.16 ± 7.93, p = 0.137) and urine cotinine level (316.51 ± 255.8 vs. 325.11 ± 263.8, p = 0.6736) were similar in both e-cig and c-cig smokers. Average time to first cigarettes of active e-cig smokers were significantly shorter than the c-cig smokers (27.92 ± 22.61 vs. 33.56 ± 23.27, p = 0.039). After adjustment for age, gender, occupation, socioeconomic and education status, the blood lead (2.11 ± 0.08 vs. 2.18 ± 0.03 vs. 1.95 ± 0.02, p = <0.0001) and cadmium (1.39 ± 0.06 vs. 1.41 ± 0.02 vs. 0.97 ± 0.01, p = <0.0001) level were significantly higher in both e-cig and c-cig smokers than never smokers. Conclusions: The amount of smoking, nicotine dependency and blood heavy metal levels of active e-cig smokers were similarly high to that of c-cig smokers.