Numerous studies have focused on both intrinsic and extrinsic variables to explain teachers' technology integration into teaching. Summarizing such studies, an encompassing construct suggests that knowledge, confidence, beliefs, and culture affect teachers' technology use. However, few studies empirically verified this theoretical construct. Moreover, despite the different circumstances and responsibilities of elementary and secondary teachers, not many scholars focused on the different relationships among the teacher-related variables in terms of technology integration. To address these gaps, this study applied an empirical dataset, which was collected from in-service teachers in South Korea, to the theoretical construct. We examined whether the variables influence teachers' technology use differently depending on the school level. Using structural equation modelling (SEM) techniques, we confirmed the significant influence of supportive culture, teachers' self-efficacy, and knowledge on teachers' technology integration except for teachers' pedagogical beliefs. In addition, the results of the multi-group SEM demonstrate differences between elementary and secondary teachers; while motivational support was the most influential variable for elementary teachers' technology use, knowledge was the most significant variable for middle school teachers. The findings contribute to the empirical understanding of what influences teachers' use of technology in practice.