The elementary science curriculum revised in 2015 initially introduced integrated units, not concerning the inquiry, but content domain. The purpose of this study is to investigate teachers’ perceptions regarding integrated units of the content domain, and to analyze their understanding and improvement requirements after teaching integrated units. Subsequently, the study offers recommendations for the next curriculum revision. The study involved surveys with teachers from elementary schools located in central Korea who had taught science in Grades 4 or 6. The questionnaires were distributed online and the data were analyzed using a statistics program. The primary results are as follows: many teachers mentioned that they comprehended integrated units while teaching them, although some others said they did not recognize the units they taught as integrated units even after teaching them. The results also showed that many students were extremely interested in integrated units and several teachers believed that teaching them was easy. However, a few teachers also regarded it as challenging. A significant number of teachers considered it desirable that the number of integrated units should be about the same or a little more compared to the current level. With regard to teaching integrated units, the teachers suggested, as requirements for improvement, the “organization of contents that enable concrete activities,” “avoiding repetition of the same content,” and “organization of material-oriented rather than concept-oriented contents.”