Background: Lung cancer has a high global incidence and mortality rate. Proper screening, prevention, and early treatment of high-risk groups are important for lung cancer. Therefore, it is important for the public to be provided with accurate information on lung cancer. This study evaluates the quality of lung cancer information provided on “YouTube”, a representative information-providing medium. Methods: We analyzed videos with more than 10,000 views among videos on “lung cancer” from YouTube. Videos were first classified into professional and nonprofessional groups according to the video providers. Text analysis was performed by extracting the subtitles from all videos. Second, the videos were analyzed based on their subtitles. Thus, the ratio of videos with misinformation to the total videos in each group was compared and analyzed. Among the videos with misinformation, those that could cause unnecessary testing or unverified treatment for viewers were additionally classified as videos with harmful information and analyzed. Results: In the nonprofessional group, 74.0% of the videos provided misinformation, which was significantly higher than 24.5% in the expert group. The proportion of misinformation videos containing harmful misinformation was 83.3% in the professional group and 92.6% in the nonprofessional group, showing no significant difference between the groups. Videos with misinformation or harmful misinformation recorded more views and comments on average, regardless of the group. Conclusion: Information from nonprofessional groups contained a higher rate of false information. However, the rate of harmful misinformation was high regardless of group.