Purpose: When pulmonary tuberculosis(PTB) patient develops, it is important to detect early and treat TB patients and latent tuberculosis infection(LTBI) for blocking TB transmission and prevention of TB through contact investigation. The present study aimed to report a result of the contact investigation that was implemented to students and staff because of a childhood tuberculosis patient case at elementary school. Methods: In a household contact screening, elementary school students who were diagnosed with LTBI in 2015 and were not treated were reported in May 2019. A chest X-ray, tuberculin skin test(TST), interferon- gamma release assay(IGRA) was performed on students and staff who had contact with TB patients. We analyzed the LTBI rate according to the characteristics of the indicator patients and the contacts by classifying them into a type of contact and status (student/ staff). Results: Among 80 contacts, there were no additional TB patients, but there were 27 LTBI(33.8%). When the results were analyzed according to the type of contact, LTBI in close contacts was 48.1%, which was higher than that of daily contacts(26.4%). According to the status, the LTBI rate of the teacher was 12.5% and the LTBI rate of students was 36.7%, which is much higher than that of the teacher. Conclusion: Including this case, most children are infected by close contact with family members, especially parents or fosterers. This report shows the importance of tuberculosis investigations and the management of household contacts. Also, childhood tuberculosis patients rarely infect other children or adults. The LTBI rate was high in this case of childhood TB patients with a cavity. It is important to detect early TB in the childhood TB patient through contact investigation.