The purposes of this research were 1) to study the relationship between knowledge of Thai language subject and anxiety in teaching of student teachers in Rajabhat Institutes, Bangkok metropolis. 2) to study the relationship from concurrence between knowledge of Thai language subject and competency in teaching Thai language of student teachers in Rajabhat Institutes, Bangkok Metropolis. 3) to study the relationship from concurrence between anxiety in teaching and competency in teaching Thai language of student teachers in Rajabhat Institute, Bangkok Metropolis. The samples for collecting data in knowledge of Thai language and anxiety were 70 student teachers in the field of Thai language in secondary education program at Rajabhat Institutes, Bangkok metropolis and the samples for observing teaching teaching behavior were 10 student teachers randomly selected from the samples in the first group. The research instruments were the knowledge in Thai language test, the anxiety in teaching scale, and the teaching behavior observation checklist. The obtained data were analyzed by Pearson product moment correlation coefficient, finding the concurrence between knowledge of Thai language subject and student teachers' competency in teaching Thai language, and finding the concurrence between anxiety in teaching and student teachers' competency in teaching Thai language of student teachers. The results of this research revealed that: 1. There was negative correlation between the knowledge of Thai language subject and anxiety in teaching of student teachers at Rajabhat Institutes, Bangkok Metropolis at 0.01 level of significance. 2. There was a correlation between the knowledge of Thai language subject and competency in teaching Thai language of student teachers at Rajabhat Institute, Bangkok Metropolis. 3. There was an inverted correlation between the anxiety in teaching and competency in teaching Thai language of student teachers at Rajabhat Institutes, Bangkok Metropolis.
