To improve self-primping characteristics, pumping characteristics, and noise characteristics.

This pump is provided with a first magnetic rotation body to be rotationally driven with the rotation of a motor, a second magnetic rotation body to be rotationally driven by the rotation of the first magnetic rotation body and constituted so as to be moved in parallel with the rotational axial direction, an impeller 22 integrated with the second magnetic rotation body, and a casing 23 for surrounding the impeller 22 and in which a step part 47 having the radial distance is increased along the axial direction separated from the first magnetic rotation body is formed on a throat part 44 radially and outward facing the impeller 22 near a discharge part for fluid in a scroll chamber formed between the impeller 22 and the casing 23.