Penelitian ini merupakan jenis penelitian tidakan (Action Research In Counseling) yang bertujuan untuk mengetahui peningkatan keterbukaan diri (self-disclosure) siswa kelas X MIA 3 SMA Negeri 2 Singaraja. Penelitian ini terdiri dari 2 siklus dimana masing-masing siklus melalui tahap identifikasi, diagnosa, prognosa, konseling, evaluasi dan refleksi. Proses pengambilan data dalam penelitian ini menggunakan koesioner keterbukaan diri pola skala likert dan dinalisis secara deskriptif serta menggunakan buku harian. Bersarkan hasil analisis, ditemukan bahwa keterbukaan diri siswa pada siklus I kategori tinggi 19 orang (68%), kategori sedang 9 orang (32%) dan tidak ada siswa yang memiliki kategori rendah dan sangat rendah.Jika dibandingkan dengan kategori skor keterbukaan diri siswa pada siklus II. Siswa dengan kategori tinggi meningkat menjadi 21 orang (75%), kategori sedang 7 orang (25%) dan tidak ada siswa yang memiliki kategori rendah dan sangat rendah. Ini menunjukan sudah ada peningkatan secara signifikan.Jadi dapat disimpulkan bahwa konseling rasional emotif teknik role playing efektif digunakan untuk meningkatkan keterbukaan diri siswa kelas X MIA 3 SMA Negeri 2 Singaraja. Kata Kunci : Konseling rasional emotif, teknik role playing, keterbukaan diri (selfdisclosure) This research belong to action research in counseling, which aimed at knowing the improvement of the students' self-disclosure level in class X MIA 3 of SMA Negeri 2 Singaraja. This research consisted of 2 cycles, in which each cycle covered several steps, namely identification, diagnose, prognose, counseling, evaluation and reflection. In this research, the data was collected through self-disclosure questionnaire in likert scale model. It was analyzed descriptively and also used researcher's diary. Based on the result of analysis, it was found that the self-disclosure level of the students in the first cycle was categorized as high category, which consisted of 19 students (68%), while there were 9 students (32%) in average category and there was no students belong to the low or very low category. The improvement can be seen if it was compared with the score category of the students' self-disclosure level in the second cycle. The number of students who had high category improved become 21 students (75%), while 7 students (25%) had average category and there was no students belong to the low and very low category. It showed that there was significant improvement in terms of the students' self-disclosure level. So that, it can be concluded that emotive rational counseling with role playing technique was effective to be used in order to improve the self-disclosure level of the students in class X MIA 3 of SMA Negeri 2 Singaraja. keyword : emotive rational counseling, role playing, technique, self-disclosure