Various factors can affect renal and patient outcome in patients with idiopathic membranous nephropathy (iMN). In this study, we analyzed the predictors of renal and patient survival in patients with iMN. We analyzed 1,776 patients diagnosed with iMN in Korean GlomeruloNEphritis STudy (KoGNET), a retrospective database of patients with renal biopsy from 1979 to 2018 from 18 centers in Korea. Cox proportional hazard regression was used to determine risk factors affecting renal and patient survival. The mean age of patients was 53.0 ± 14.7 years old and 1,075 (60.5%) were male. At the time of renal biopsy, 755 (46.0%) and 266 (16.2%) had hypertension and diabetes, respectively. Serum albumin level was 2.7 ± 0.8 g/dL and 871 (49.0%) had nephrotic range of proteinuria. Median duration of follow-up was 88.0 (38.0 – 115.1) months. Complete or partial remission rates were 48.5%, 63.8%, and 68.0% at 6 months, 12months after biopsy, and last follow-up, respectively. In Cox proportional hazard regression, high hemoglobin [HR 0.66 (0.47 – 0.93), p=0.017], high serum albumin level [HR 0.41 (0.18 – 0.94), p=0.034], and high estimated GFR by CKD-EPI equation [HR 0.94 (0.91 – 0.96), p<0.001] at biopsy were good predictors for renal outcome, whereas presence of cerebrovascular disease at biopsy [HR 6.45 (1.16 – 35.71), p=0.033] were poor prognostic factors for ESRD. Age 65 and older [HR 3.26 (1.53 – 6.95), p=0.002] and presence of hypertension at biopsy [HR 2.45 (1.09 – 5.54), p=0.031] were significant risk factors for patient survival. High hemoglobin and serum albumin, and good renal function at biopsy were good predictors for renal survival. Older age and hypertension at biopsy were poor prognostic factors for patient survival in iMN patients. Prognostic information of outcomes in this study might be helpful to optimize management in iMN patients.