The purpose of this study is to investigate implications for future STEAM education by analyzing the surveys by the in-service teachers who participated in the Advanced STEAM Teacher Training Program(ASTTP) for raising interests and understanding of science and technology and nurturing STEAM literacy and problem-solving ability of students. ASTTP was developed for promoting 'teacher competence for STEAM.' ASTTP is a 60-hour program(4 credits), which includes offline intensive course of 38 hours, online training course of 12 hours, a course of implementation at schools for 5 hours, and a workshop for 5 hours (based on the 2014 program). For the offline intensive course, teachers take various professional development classes and activities, such as open-laboratory tours, advanced experiments, mentoring programs, and team projects as well as lectures on diverse disciplines. For the online course, teachers take online classes freely while they are encouraged to work with other teachers in groups. After taking both online and offline courses, the teachers are required to implement their STEAM lesson plans in their classrooms. Finally at the workshop, some selected teachers share how successfully they have implemented STEAM education. About 700 teachers have successfully taken the program from 2012 to 2014. Based on the surveys by the teachers, the program has been modified and improved. Our analysis shows increased professional development in STEAM education for the participating teachers. This study can provide some implication and helpful insights for people who need to develop and manage teacher training programs for STEAM education and other education programs in general.