The invention provides a mainshaft motor, which is capable of preventing generation of lubricant leakage during high-speed rotation. The mainshaft motor includes: a stator 23 having a motor base plate 5; a bearing 6 fixed on the motor base plate 5; a bearing holder 7; a mainshaft 4 free-pivotly kept on the bearing 6; a free-rotary rotor 1 fixed on the mainshaft 4 opposited to the stator 23. A lubricating oil cycle device 15, placed in the gap between the inner circumference of the bearing holder 7 and the periphery of the mainshaft, and placed at least contiguous to one edge of the bearing 6 in axial direction of the mainshaft 4, can allure the lubricating oil outflowing the bearing 6 by the capillary phenomenon, reflow them to the bearing 6.. |