To provide a technology for improving a pump efficiency by reducing sliding resistance between an impeller and a casing.

The fuel pump is equipped with a substantially disk-shaped impeller 20 and a casing 14 for rotatably housing the impeller. Permanent magnets 26 are arranged in the impeller 20. Driving coils 40 are arranged in the casing 14. By so doing, the impeller 20 is rotated when power is applied to the driving coil 40. The supporting device 42 for supporting the impeller 20 by a rolling element brought into rolling contact with the impeller 20 is provided to the vertical surface of the impeller 20 and the casing 14 inner surface opposed thereto.