This research aims to find out the reliability of the Tazkiyatun Nafs Module. The module consists of three sub-modules which are Tarbiyah Asasiyah (basics education of religion), Tarbiyah Ma'rifatullah (the process of knowing Allah) and Tarbiyah Mawaddah Warahmah (the process of education through love and care). The participants of this study consisted of seven experts and 50 secondary school students. The participants were treated using the Tazkiyatun Nafs Module. A questionnaire was used as a research instrument in finding the reliability of the module. Questionnaires on Sub Module 1: Tarbiyah Asasiyah, Sub Module 2: Tarbiyah Ma'rifatullah, Sub Module 3: Tarbiyah Mawaddah Warahmah were used to determine the coefficient value of the reliability of the Tazkiyatun Nafs Module. The collected data were analyzed using Alpha Cronbach. The findings show that the Alpha Cronbach's value for the sub module 1 is 0.720, the sub module 2 is 0.809, the sub module 3 is 0.770, while the overall Alpha Cronbach value of the Tazkiyatun Nafs Module is 0.772. Finally, some implications were also discussed based on the findings of this study.