To provide an adapter device having a structure capable of mounting a honing tool on the rotary spindle of a honing machine simply and removably without rotational deflection or tumbling.

A pull-stud fixation part 7 to engage a tool holder 6 holding rigidly a honing tool 1 fast with a holder holding part 5 provided at the forefront of a rotary spindle 2 is furnished with an operation part 47 at the periphery of the spindle 2, and even a honing machine of such a structure as having a whetstone expanding mechanism in the central part of the spindle 2 can adopt an operating system similar to the pull-stud drawing system used generally in a machining center, etc., and it is made practicable to mount and remove the honing tool 1 simply and quickly. Deflection absorbing parts 8 and 9 to adjust the axial position of the honing tool 1 relative to the axis of the spindle 2 are provided in the connection part of the spindle 2 side as reference for mounting with the adapter side, and it is possible to set so that the axis of the tool 1 is positioned coaxially to the axis of the spindle 2 precisely.