A critical component of teacher effectiveness is how teachers notice students' misconceptions and adjust the instructional approach accordingly. Taking a stance that the teachers' instructional quality is crucial to students' learning, a qualitative international comparison study was performed to examine science teachers' perceptions of and their approaches toward students' misconception on photosynthesis between the United States (US) and South Korea. A web-based on-line survey consisting of open-ended questions was administered to secondary science teachers and 85 and 81 teacher responses were collected from the US and Korea, respectively. Constructed responses were analyzed using the constant comparative method and enumerative approach through which regularities and patterns in the responses emerged. Four categories emerged concerning teacher perceptions of misconceptions: Concept, Knowledge Construction, Curriculum, and Pedagogical. Most teachers employed Concept or Knowledge Construction perspective to identify and reason out student misconceptions in both countries. In respect to instructional strategies, two dominant patterns emerged: content-focused and student-focused strategies. Teachers from both countries demonstrated the most frequent use of content-centered approaches, although the patterns of the usage in relation to their perceptions towards misconceptions were different to some degree. Possible attributing factors for the observed patterns and some limitations of the study are further discussed.