An index apparatus for an NC machining center which machines a work having a predetermined length, the apparatus comprising: a main table; first and second housings (2a, 2b) mounted on the main table and away from each other; first and second index tables (4a, 4b) configured to hold the work and supported on the first and second housings (2a, 2b) for rotation; a first push bar supported on the first housing for movement; a second push bar supported on the second housing for movement; an NC device including a spindle, the NC device being configured to make an extra relative movement between the spindle and the main table other than a machining relative movement between the spindle and the main table in such a manner that the first push bar is moved by the extra relative movement; a push bar transmission mechanism mounted in the first housing and disposed between the first push bar and the first index table, the push bar transmission mechanism being configured to rotate the first index table in response to the movement of the first push bar; a first locking mechanism mounted in the first housing, the first locking mechanism being configured to lock the first index table, the first locking mechanism being configured to unlock the first index table when the first push bar is moved; a second locking mechanism mounted in the second housing, the second locking mechanism being configured to lock the second index table, the second locking mechanism being configured to unlock the second index table when the second push bar is moved; and a relative movement transmission mechanism disposed between the first and second housings (2a, 2b), the relative movement transmission mechanism being configured to unlock the second index table in response to the extra relative movement between the spindle and the main table in such a manner that the second push bar is moved by the extra relative movement; wherein the work and the second index table are rotated by the rotation of the first index table integrally so as to index the work, and the push bar transmission mechanism is configured to rotate the first index table after the first and second index tables (4a, 4b) are unlocked. a main table; first and second housings (2a, 2b) mounted on the main table and away from each other; first and second index tables (4a, 4b) configured to hold the work and supported on the first and second housings (2a, 2b) for rotation; a first push bar supported on the first housing for movement; a second push bar supported on the second housing for movement; an NC device including a spindle, the NC device being configured to make an extra relative movement between the spindle and the main table other than a machining relative movement between the spindle and the main table in such a manner that the first push bar is moved by the extra relative movement; a push bar transmission mechanism mounted in the first housing and disposed between the first push bar and the first index table, the push bar transmission mechanism being configured to rotate the first index table in response to the movement of the first push bar; a first locking mechanism mounted in the first housing, the first locking mechanism being configured to lock the first index table, the first locking mechanism being configured to unlock the first index table when the first push bar is moved; a second locking mechanism mounted in the second housing, the second locking mechanism being configured to lock the second index table, the second locking mechanism being configured to unlock the second index table when the second push bar is moved; and a relative movement transmission mechanism disposed between the first and second housings (2a, 2b), the relative movement transmission mechanism being configured to unlock the second index table in response to the extra relative movement between the spindle and the main table in such a manner that the second push bar is moved by the extra relative movement; wherein the work and the second index table are rotated by the rotation of the first index table integrally so as to index the work, and the push bar transmission mechanism is configured to rotate the first index table after the first and second index tables (4a, 4b) are unlocked.