The present invention is an invention that aims to provide a technique for designing and evaluating an artificial lung that can comprehensively examine the performance of each element of the oxygenator and that can exhibit comprehensively excellent performance. An oxygenator comprising a gas exchanger part having an external perfusion-type hollow fiber membrane bundle and a heat exchanger part having a heat exchange element, the heat exchange performance coefficient of the oxygenator, the blood filling amount of the oxygenator and the oxygenator Blood pressure loss is measured, Fp3 = heat exchange performance coefficient of oxygenator / (blood filling amount of oxygenator × blood pressure loss of oxygenator), and oxygenator with Fp3 value of 0.15 or more I will provide a.本発明は、人工肺の各要素の性能を統一的に検討でき総合的に優れた性能を発揮できる人工肺を設計し評価する技術を提供することを目的とする発明であり、ガス交換用の外部潅流型中空糸膜束を有するガス交換器部および熱交換用エレメントを有する熱交換器部を備える人工肺であって、人工肺の熱交換性能係数、人工肺の血液充填量および人工肺の血液側圧力損失を測定し、Ｆｐ３＝人工肺の熱交換性能係数／（人工肺の血液充填量×人工肺の血液側圧力損失）を計算し、Ｆｐ３の値が０．１５以上である人工肺を提供する。
