The use of the Indonesian language, particularly in spelling, has not been fully executed properly, especially in textbooks. Textbooks, especially Indonesian language textbooks, as the primary learning source, should serve as examples of standardized and error-free texts. However, in reality, many language errors are still found in the non-fiction texts of Indonesian language textbooks. This research describes syntax language errors in the Indonesian Language Textbook for Grade VIII published by the Curriculum and Book Development Center of the Ministry of Education and Culture. The research method used is Qualitative Descriptive. The results of the research include language errors in the Grade VIII Indonesian Language Textbook published by the Curriculum and Book Development Center of the Ministry of Education and Culture in the field of syntax, which include: conjunction errors, punctuation errors, misspellings not in accordance with KBBI (Indonesian Dictionary), and sentence ineffectiveness. From the research findings, it can be concluded that Indonesian language textbooks serve as good learning resources, but the various errors found indicate that Indonesian language textbooks are still not effective for learning. This research was conducted to identify language errors in Indonesian language textbooks in order to pay more attention to their effectiveness in learning.