A screw pump includes a male screw, a female screw, a motor, a journal, a bearing member, and a case. The motor includes an output shaft, which transmits a torque to the male screw, and the motor is operable to drive the male screw to rotate the same through the output shaft. The journal is rotatably placed between the output shaft of the motor and the male screw. The bearing member rotatably supports the journal. The case includes a screw receiving hole that receives the male screw and the female screw. The journal and the male screw are coaxially and non-detachably integrated together. The output shaft and the journal are fitted together by clearance fit that enables transmission of the torque between the output shaft and the journal.