Disclosed is a convergence machining apparatus based on turning in which a rotation center of a work piece to a headstock and a footstock and a slide surface of first and second beds mounted with a reciprocal carriage, the headstock, and the footstock are positioned on the same virtual line when viewed from a direction parallel with a rotation axis of the work piece, thereby preventing an offset error in processing due to a relative displacement between the work piece and a tool installed at the reciprocal carriage.