The purpose of this research was to study the state and problems of professional experience training of biology student teachers in the Faculty of Science and Technology, Nakhon Pathom Rajabhat University. The sample was 31 biology student teachers, Program of Biology, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, and 26 mentors The research instruments were two questionnaires; 1) questionnaire for biology student teachers, and 2) questionnaire for mentors. The statistics used for data analysis were frequency, percentage, mean and standard deviation. The results indicated that there were 3 high level of problems according to the perception of biology student teachers; teaching preparation, teaching operation, and the classroom action research, and 6 moderate level of problems; teaching media, student teachers, students, supervisors, mentors, and professional experience training school. In addition, there were 8 moderate level of problems according to the perception of mentors; teaching media, teaching preparation, student teachers, teaching operation, professional experience training school, classroom action research, students, and mentors, while the problem about supervisors was at a low level.