The CO2 injection pump plays an active role as a part of the Enhanced Oil Recovery (EOR) process that injects carbon dioxide (CO2) into the oil layer and recovers crude oil efficiently. When this process is performed, carbon dioxide, which is collected from emitted gas at the energy production or other industries, is utilized in some cases. There is high expectation for the oil recovery process because it can also serve as a carbon capture and storage (CCS) process for preventing the release of the large quantities of carbon dioxide into the atmosphere. This article introduces the roles and characteristics of the CO2 injection pump as an application example of a high-pressure pump.