A spindle unit includes: a main spindle that holds a rotary tool, and that is rotated; bearings by which the main spindle is rotatably supported; and a damper bearing by which the main spindle is rotatably supported, and that has a damping coefficient larger than damping coefficients of the bearings. The damping coefficient of the damper bearing is set to a value within a range from 10,000 to 1,000,000 N·s/m.