Marital distress and marital relationship problems are effective in generation and acceleration of depression. Depression is a significant contributor to the global burden of disease and affects people in all communities across the world. This study aims to determine the effectiveness of emotion-focused cognitive therapy in decreasing depression caused due to marital relationship problems. The design of this study was semi-experimental with pre-test, post-test and control group. The research population consisted of all couples referred to the Ferdowsi University of Mashhad Clinic of Psychology. 10 couples with marital problems were selected by convenience sampling, and randomly assigned to an experimental group and a control group. The experimental group received emotion-focused cognitive therapy while the control group received no treatment. The research measurement instruments consisted of BDI-II and CPQ. ANCOVA models were used to test the study hypothesis. The results showed that EFCT had been effective in decreasing depression due to marital relationship problems (P < 0.001). The results of our study not only demonstrated that the importance of cognition and emotion in marital relationship but also product useful information about effectiveness of EFCT on depression caused due to marital relationship problems for researchers, counselors and psychotherapists.