Lathe positioning apparatus

The purpose of the present invention is to provide a lathe positioning apparatus such that a work held by a chuck can be positioned at an arbitrary position in main shaft direction and the installation space and the size of the apparatus can be decreased. A lathe positioning apparatus for positioning a work W held by a chuck in a main shaft direction is provided with an apparatus body having a shaft center along the main shaft direction. An abutting portion for abutting the work W is formed on a chuck side end of the apparatus body . A mechanism for advancing or withdrawing the abutting portion with respect to the chuck is provided. An extension/contraction mechanism for extending or contracting the apparatus body in the main shaft direction is provided in the apparatus body . The abutting portion is advanced or withdrawing with respect to the chuck by the extending or contracting by the extension/contraction mechanism.