Background: The 30-item Questionnaire for Triage and Assessment (QTA30) is a standardized triage and assessment tool for assessing pediatric psychosomatic disorders. It is estimated that one in 10 children in Japan experience difficulties in their school life. Using the QTA30 we evaluated mental health in children at an outpatient clinic in a local hospital. Methods: All elementary and junior high school students (≥9 years) who visited our institution between December 1 2019 and March 31 2020 were asked to complete the QTA30. Result: A total of 372 children responded. Half of the children with a psychosomatic disorder and 9% of children with other chronic disorders were suspected to have poor mental health. Suspected poor mental health was associated with higher odds of female gender (odds ratio [OR]: 1.89, 95% confidence interval [CI]: 1.07-3.39), junior high school students (OR: 3.73, 95% CI: 2.11-6.73), and not enjoying exercise (OR: 2.13, 95% CI: 1.16-3.9). The mean AE standard deviation total QTA30 score was significantly worse in children with psychosomatic disorders (38.0 AE 19.1) among children with other chronic diseases; however, only the score in children with central precocious puberty (27.4 AE 13.7) showed no difference. Conclusion: Based on our survey, the percentage of children suspected to have mental health problems manifesting as non-psychosomatic chronic disorders was similar to the proportion of children suspected to experience difficulties with their school life. Pediatricians should carefully consider the possibility of mental health problems when children are seen in regular visits to the outpatient clinic.