This article aims to describe the characteristics of professional Indonesian teachers in Indonesia. This presentation is based on two things, namely (1) Halliday's view of language and (2) findings of problems relating to students, teachers, and Indonesian subjects. The problem relates to the negative connative aspects of the students. Students often use Indonesian non-bicultural languages in a formal context. Meanwhile, according to Halliday's view, language is used based on the context of the situation. These issues then highlight the professionalism of Indonesian teachers in Indonesian language subjects. This professional characteristic of Indonesian teachers can be a guide for Indonesian language teachers to improve their professionalism related to the subjects they have.