A spindle unit includes: a main spindle (20) that holds a rotary tool (21), and that is rotated; bearings (41 to 44) by which the main spindle (20) is rotatably supported; and a damper bearing (50) by which the main spindle (20) is rotatably supported, and that has a damping coefficient (C1) larger than damping coefficients (C2 to C5) of the bearings (41 to 44). The damping coefficient (C1) of the damper bearing (50) is set to a value within a range from 10,000 to 1,000,000 N.s/m.