Objectives: The self-management of chronic diseases is currently receiving much attention. This study applied an extended technology acceptance model (ETAM) to analyze the factors influencing acceptance of a healthcare smartphone application. Methods: Three hundred people living in Seoul and Gyeonggi who used smartphones were quota sampled. A telephone survey was conducted using a structured questionnaire based on ETAM. A path analysis was carried out using the AMOS 17.0 program, and the model was verified. Results: The analysis revealed significant factors of perceived usefulness (.374, p < .001), enjoyment (.210, p < .001), subjective norms (.168, p < .001), perceived costs (.146, p < .001), and innovativeness (.138, p < .001). Cost directly influenced intention to use health applications; self-efficacy and perceived ease of use indirectly affected intention through innovation and perceived usefulness. Conclusions: This study helped to identify the main factors that influence usage intention of smartphone applications. These findings could contribute to promoting the self-management of chronic disease through future health applications using smartphones.