Background: Determine factors influencing the continuance intention of the Quit & Win smartphone app based on the technology acceptance model (TAM). Methods: This cross-sectional study was conducted on volunteer military personnel who smoke. Participants were asked to download a smoking cessation app and use it for 15-20 minutes before completing a questionnaire. Items in the questionnaire included those on demographic information, perceived usefulness, perceived ease of use, and continuance intention. The structural equation modeling (SEM) was applied to evaluate the TAM. Results: A total of 90 participants were included in this study. The model accounted for 0.81 of the variance in participants’ intention to continue using the app. The results revealed that perceived usefulness affected continuance intention, self-efficacy affected perceived ease of use, and perceived ease of use affected perceived usefulness. Conclusions: This study applied the TAM to determine the factors influencing the continuance intention to use a smoking cessation app and revealed that perceived usefulness is the most crucial factor affecting continuance intention. Therefore, future designers of smoking cessation apps shall improve perceived usefulness to increase the continuance intention of users.