Extracorporeal cardiopulmonary resuscitation (ECPR) requires advanced skills for induction and management. This study evaluated whether the outcomes of ECPR differ by institutional volume. Using the Japanese Association for Acute Medicine–Out-of-Hospital Cardiac Arrest (JAAM-OHCA) registry, we analyzed adult patients (aged ≥18 years) who received ECPR between 2014 and 2020, focusing on 30 day in-hospital survival and favorable neurologic prognosis at 30 days defined as Cerebral Performance Category (CPC) 1–2. Facilities were categorized into tertiles by annual ECPR volume. Multivariable logistic regression examined outcomes across low (≤4.7 cases/year), medium (4.8–7.8 cases/year), and high (≥7.9 cases/year) volume groups. A total of 1,759 patients from 83 centers were included, with an overall 30 day survival of 21.1% and CPC 1–2 rate of 10.1%. We observed no statistically significant differences in the respective rates of 30 day survival and neurologic outcomes in the medium ECPR volume group (adjusted odds ratios 1.09 [95% confidence interval {CI}, 0.82–1.47] and 0.85 [0.56–1.26]) and higher ECPR volume group (adjusted odds ratios 1.27 [95% CI, 0.95–1.70] and 1.11 [0.75–1.63]) compared with the lower ECPR volume group. These findings suggest that ECPR outcomes for out-of-hospital cardiac arrest are not significantly affected by institutional ECPR volume.