To improve pump efficiency even if an axial flow pump of a liquid-cooled system of an electronic device is downsized, to ensure the reliability of rotation of a rotor and to ensure that cooling liquid is prevented from dissipating with a simple configuration.

A rotor 21 of a cylindrical ferrite magnet having a hollow portion 23 is placed turnably in cooling liquid with a small gap on the inner side of a metal pipe 20 with a certain inner diameter and a diameter of an impeller 24 formed integrally on the outside of an end portion of the rotor 21 is made equivalent to the inner diameter of the pipe 20. The rotor 21 is polarized into symmetric two poles and configured of three stator coils 26 and 27 or may be configured of one stator coil.