Tool post for machine tool

A tool post for a machine tool comprising:

• a supporting member that movably supports a tool;
• a driving force transmission part that is disposed between the supporting member and the tool to transmit driving force to the tool, the driving force transmission part comprising an engaging member that is located in a side of the supporting member, and an engaging member that is located in a side of the tool, and the engaging members engaging in accordance with a movement of the tool, at least one of the engaging members provided to be biased to an engaging posture in which both of the engaging members are capable of engaging;
• and
• a releasing member that is disposed between the side of the tool and the side of the supporting member, and releases the engaging posture by pressing the engaging member against a biasing force,
• wherein a driving force is transmitted to the tool via the driving force transmission part by moving the tool to a predetermined position where the both of the engaging members engage, and
• wherein the releasing member is disposed to release the engaging posture by pressing the engaging member in the middle of the movement of the tool toward the predetermined position, the engaging member is biased to the engaging posture when the engaging member is in a disengaging state, and to release the pressing when the tool reaches the predetermined position to engages the both of the engaging members.