A machine tool includes: a spindle head; a spindle rotatably supported on the spindle head; a chuck unit configured to chuck a tool inserted in an axis direction of the spindle; a tool holder configured to hold the tool attached to the chuck unit; and a rotary arm configured to move the tool holder to a reachable position of the spindle. The tool holder is supported on the rotary arm by a support mechanism, and the support mechanism includes a displacement following mechanism configured to support the tool holder on the rotary arm in a manner to be capable of displacing the tool holder in a direction intersecting an axis of the tool.

In order to be suitable for space-saving of a multi-functional processing machine in which a tool main spindle device is disposed at a center of an opposed biaxial lathe, there is provided an automatic tool exchanger provided in the multi-functional processing machine, the automatic tool exchanger including: a tool magazine that is disposed in a machine body front surface upper portion of the multi-functional processing machine and is configured to house multiple tools for exchange with respect to the tool main spindle device; a shift device configured to move the tool between the tool magazine and a tool exchanging position with respect to the tool main spindle device; and a tool changer configured to exchange the tool between the shift device and the tool main spindle device.