This study explored the effects of the preservice biology teachers’ attitude toward convergence, problem solving ability and pedagogical knowledge after STEAM education program. The participants are 16 preservice biology teachers. The STEAM education program consists of learning about STEAM education, engaging in STEAM classes with four science-related topics, development of STEAM teaching-learning materials, and reflecting about experiences of STEAM education as both standpoints of students and future teachers. The classes were video-recorded and transcribed to concretely examine the preservice teachers’ attitude toward convergence and problem solving. The results indicated that the preservice teachers significantly increased their scores on attitude toward convergence and problem solving ability. In the reflective journals, the preservice teachers mentioned that they arose interest on STEAM topics related to everyday life and were immersed in the processes of problem solving. They also mentioned that they engaged in active communication during the stages of creative design and emotional touch. Even though the preservice teachers mentioned the difficulties of development of STEAM lesson and the time constraints for preparation of a STEAM class, they perceived the necessity of STEAM education in schools. The preservice teachers further suggested cooperative learning through questioning and communication as STEAM teaching and learning methods. This study implicated that the preservice teachers built the practical knowledge of STEAM education through apprehending advantages and supplementing the weaknesses.