This research which uses qualitative research is intended to find out and identify the main cause of the reluctances of using Acehnese among its teenagers. Language attitude concentrates on the individual speaker’s attitudes towards his own language use, in this case the mother tongue. As a result of the attitude, young speakers are losing the positive attitude toward their mother tongue and shifting to another language, which is the national language Bahasa Indonesia. Students aged 13 – 14 in SMPN 15 Lamjamee, Banda Aceh were taken purposively as subject of this research. For data collection, the researcher uses two techniques such as observation and interview. The observation and interview data show that the students are reluctant to use Acehnese in the public places or with their peers because (1) it is embarrassing to use Acehnese, (2) it will give them bad name or bad judgment, and (3) it brings uncomfortable experiences. The causes prevent them to communicate the language with their peers, since the cultural encounter and social treatment created the negative attitude of the Acehnese teenager’ users. Therefore, Acehnese teenagers are suggested to lessen their reluctances in order to preserve their mother tongue.