The purpose of this longitudinal study was to explore the developing process of college students'consciousness about the teaching profession and the changes in their motivation to be a teacher during 4-yearsteacher training education. By means of the Modified Grounded Theory Approach, the protocol data of sophomores' interview about their consciousness about the teaching profession and motivation to be a teacherwere analyzed and the developing process of them was illustrated. The outcome of this study was considered as compared with some antecedent studies and the study. It was discussed how to keep or increase students' motivation to be a teacher during 4 years, and it was suggested that getting the skills and knowledge about teaching reduces students' anxieties about giving classesby themselves.