The purpose of this study is to identify the factors that influence users' intention to use mobile services in academic libraries, based on the Davis' Technology Acceptance Model. This study employed both perceived usefulness and perceived ease of use, which were core variables in TAM, and added perceived playfulness that was recently applied to many researches on mobile system acceptance intention. As external variables, ubiquitous ability, context awareness, and mobile internet self-efficacy were employed. The data was collected from 325 surveys from two academic libraries and was analyzed with SPSS 18.0 and AMOS 21.0. As a result, perceived usefulness was the most significant factor in predicting users' acceptance intention and perceived ease of use was an indirect determinant of service usage. But perceived playfulness was not significantly correlated. Ubiquitous ability among external variables had a significant effect on perceived usefulness, context awareness did on both perceived playfulness and ease of use, and mobile internet self-efficacy did on perceived ease of use. Based on the findings, this study discussed theoretical and practical implications in academic library mobile service area.