Objective This study examined the mediating effect of mindfulness and consciousness among five factors on the effect of stress on Internet game addiction tendency. Methods An online survey was conducted on 400 men and women between their 20s and 40s across Korea. The scales used in the study were the Internet game addiction scale based on the DSM-5, Perceived Stress Scale, Mindfulness Scale, and Five-Factor Personality Scale. For data analysis, structural equation modeling was conducted, and Sobel verification was carried out to verify the significance of the mediating effects. Results The results of the study are as follows: Stress showed a positive correlation with Internet game addiction tendency, mindfulness mediated the effect of stress on Internet game addiction tendency. Conclusion Of the five personality factors, conscientiousness also mediated the effect of stress on Internet game addiction tendency. This study highlights the need for further research for individuals with game addiction tendency.