This study investigated teachers’ perceptions of the inquiry unit in fifth- and sixth-grade science textbook in the 2015 revised national curriculum. In this study, 108 fifth- and sixth-grade teachers at elementary schools located in Gyeonggi province were selected. In this study, first, the teachers’ perceptions of the necessity and effectiveness of the inquiry unit were investigated. A positive perception of the necessity of this unit was indicated, and it was recognized that it effectively developed integrated science inquiry skills. After completing the unit, the teachers recognized its effectiveness for promoting student inquiry-learning for other units. Second, the teachers’ opinions on the guidance of the inquiry unit in the fifth and sixth grades were investigated. The inquiry unit’s topic was considered appropriate, although negative opinions on the difficulties of the inquiry topic were also presented. Overall, teachers supported maintaining the size of the unit, and it was reported that the students were generally interested in the inquiry activities. However, 32.4% of the respondents had difficulty teaching a unit. Additionally, 47.2% answered that they taught the contents presented in the textbook as is, and 40.7% indicated that they taught by restructuring, marking a similar rate. In addition, they responded positively to the effects of the experimental methods, photos, and illustration materials presented in the textbook, as well as the need to present additional reading materials.