The main purposes of this study are to identify major factors in subject teaching performance of junior high school intern teachers, to make comparative analysis of the cited performance of normal and non-normal university graduates, and to investigate the interrelationships of subject teaching performance, subject teaching knowing and subject teaching belief. Research questionnaires were sent to 1,995 interns at 409 junior high schools. Valid questionnaires were secured form 1,217 interns (61%). Five principal results are stated as follows: 1. Seven major factors were identified in subject teaching performance. 2. Among 4 out of 7 major factors, factor average of non-normal interns were significantly higher than those of normal interns in t test. 3. The correlation coefficients of subject teaching performance with subject teaching knowing and subject teaching belief were statistically significant. 4. Subject teaching knowing was strongly related to "total of subject teaching performance," "performance in planning for instructional modules, subject matter and teaching aids," "performance in handling with teaching skills," "performance in applying instructional measurement outcome," and "performance in individualized instruction." 5. Subject teaching belief was strongly related to "total of subject teaching performance," "performance in planning for instructional modules, subject matter and teaching aids," and "performance in handling with teaching skills."