PURPOSE: To improve the life of a bearing bush in a screw pump by rotating an integral tubular shaft part at the same time when a screw shaft body rotates by driving the screw pump, and bringing the whole internal periphery of the bush inserted in the tubular shaft part into contact with a fixed shaft.

CONSTITUTION: When a screw shaft body 1 rotates, a bearing part 21 rotates. A bearing bush 13 inserted in the internal surface of the bearing part 21 rotates while its whole periphery is being brought into contact with a part of upper section of a fixed shaft 25. Therefore, the internal periphery of the bearing bush 13 is worn uniformly without only a particular part worn, thus increasing its life. Because the bearing part 21 is arranged downwards to its opening side, dust, sewage sand or the like will not invade its inside, so it is possible to prevent its inside from being worn.