This study was undertaken to investigate the general attitude toward science and scientific inquiry behavior of underachiever at the junior high school level. In this study, underachiever was defined as the one who is below the minimum acceptable performance level because of his/her deficiencies in prerequisites but who has the capability to reach the required mastery level in normal classroom. For the identification of the underachiever, IQ test and achievement test in science which were developed by the investigators were used. The attitude test which was to measure the general attitude toward science and scientific inquiry behaviors of the underachiever was also developed by the investigators. The tests were given to 250 1st grade junior high school students in one experimental school. Out of 250, 55 underachievers were identified. For the study, 55 underachievers with 57 normal students were compared. The findings of this study showed that there were significant differencies between underachievers and normal students in both attitude toward science and scientific inquiry behavior. They can be summarized as follows; 1. Awareness on science by underachievers was minimal compared to normal students. 2. Compared to normal students, there was a tendency by underachievers to think the influence of science on their real life is remote. 3. Underaschievers were less positive, less voluntary and were less persistent in science activities than normal students. 4. Underachievers were less interested in science than normal students. These findings showed us that there were significant relation between the attitude and achievement level. This suggests that fostering attitude toward science and scientific inquiry behavior is needed for the improvement of achievement level of underachievers.