In a pump conveying a supercritical fluid or a liquid are provided stator slots and motor mold members which are charged between the stator slots, so as to have a stator can of a motor driving the pump from the outside thereof. Additionally, by providing a main shaft of a motor driving the pump and bearings supporting the main shaft with clearance-fitting and by tightening inner rings of the bearings to the main shaft in an axial direction, the bearings are fixed to the main shaft.