Electric oil pumps (EOP) for automobiles are used to lubricate and cool moving mechanisms and supply oil pressure to components. Conventional EOPs consist of two separate units including a driver and a pump system comprised of a motor and a pump, which, as a result, impedes layout flexibility for vehicles. To overcome this shortcoming, we have developed an ECU-integrated oil pump in which a driver, a motor and a pump are incorporated as a single unit. In the course of the project, we focused on improving vibration resistance and developing a compact design. The first challenge was to improve vibration resistance because of the driver located in close proximity of the powertrain. Since the driver is installed on the motor unit via bus bars that are electrically welded, the joints of the driver and the bus bar become susceptible to vibration. To resolve this, the newly developed spring plate is inserted in the limited space between the bearing holder and the bus bar ring, which has significantly reduced resonance of the bas bar ring. The next focus was to develop a compact design by shortening the shaft length and developing a highly efficient internal gear pump. The shaft length is significantly reduced by fewer bearing parts and the single shaft design for the motor and the pump. The total shaft length is 27% shorter and our EOP is 10% lighter, compared to conventional EOPs. As for the efficiency, the optimum clearance for a wide temperature range from -30°to 130°is obtained through validations of prototypes and applied to the design. The total efficiency of the motor and the pump exceeds 50%, which is double the efficiency of conventional EOPs. With these technologies, we have successfully developed a compact and highly-efficient ECU-integrated oil pump that offers greater layout flexibility.