We report on annealing behaviors of electrical and optical properties of In-doped CdTe to investigate the self-compensation in high-resistivity CdTe. A characteristic luminescence line at 1.5842 eV in high-resistivity In-doped CdTe is found to be due to emissions from bound excitons trapped at compensating related defects, which is ascribed to a Cd-vacancy/indium complex. These defect complexes act as accepters and are responsible for the self-compensation through the balance between the doped indium donors and the defect complex accepters. Magneto-optical measurements also support this self-compensation mechanism.