Spindle device

A spindle device, comprising:

• a housing formed with a support hole;
• a spindle which is supported to rotate freely about an axis within the support hole of the housing and to which a tool is attached;
• a first drive motor for rotating the spindle about the axis;
• and
• controlling means for controlling an operation of the first drive motor, wherein the first drive motor is configured by a first rotor arranged to rotate freely on an outer circumferential surface of the spindle and a first stator fixedly provided on an inner circumferential surface of the support hole of the housing in a manner to be kept apart by an interval toward a radially outward direction from an outer circumferential surface of the first rotor,
• the spindle device comprising coupling means configured to perform a coupling operation for coupling the spindle and the first rotor and an uncoupling operation for uncoupling between the spindle and the first rotor, wherein the controlling means controls the operation of the coupling means.