PURPOSE: To minimize a bearing part for small-sizing the whole body of a pump by arranging various bolts almost on the same circle, and to adapt these various bolts for fine adjusting in the axial position of a runner easily by the operation of shifting from the outside.

CONSTITUTION: When various bolts 4, 5 and 29 are arranged almost on the same circle, the whole part of a bearing 7 is minimized, and the whole body of a pump can be brought into a compact size. For adjusting a runner 25 finely in an axial direction in a pump casing, when an inner bolt 4 is screwed toward an inside bearing cover 2, the bearing 7 and a shaft 6 are shifted finely by a contact part 2a as an arrow A shows. When an outer bolt 5 is screwed into a bearing housing 1, an outside bearing cover 3 is pushed to the inside, and the bearing 7 and the shaft 6 are shifted finely by a contact part 3a as an arrow B shows for adjusting a gap 38 between a runner 25 and a control plate 28 easily.