I reported Korean IME bug to QT Bug report. Please refer to below link. https://bugreports.qt.io/browse/QTBUG-136128?jql=text%20~%20korean%20ORDER%20BY%20created%20DESC But, QT reponsed me like follwing. Thank you for reporting. However, this issue seems like a known issue with apple's Korean IME. There are many threads in Korean community about the same problem with Non-Qt apps. If this issue is a really Qt issue, feel free to open it again. Is there any workaround to fix this IME bug ? Thanks, Ted