Abstract: A spindle device 20 includes: a bracket 21 swingably mounted on a support arm 9 and having a tubular portion 22 substantially perpendicular to the swing axis of the bracket 21; and, a spindle 30 including a rotation portion 31 capable of mounting a tool onto the leading end thereof, a housing 32 insertably and removably mounted on the tubular portion 22 of the bracket 21 and having a mounting surface 35a disposed opposed to the surface of the bracket 21, and bearings 50 and 51 respectively interposed between the rotation portion 31 and housing 32 for supporting the rotation portion 31 rotatable relative to the housing 32. In the mounting surface 35a of the housing 32, there are formed flow passage openings 80˜86 for fluid which are supplied to the spindle 30.