NC automatic lathe

An NC automatic lathe including abase board, a headstock provided with a main spindle and so arranged as to move in a direction of Z axis, a back attachment provided with a sub spindle which is so arranged as to be opposed to the headstock, the back attachment being so arranged as to move in directions of Z axis, X axis and Y axis, a guide bush, a first turret tool post arranged at a side of the guide bush so as to move in directions of X axis and Y axis, a second turret tool post arranged at a side of the guide bush so as to move in directions of Z axis, X axis and Y axis, and a fixed back machining tool unit arranged at a position offset with respect to at least one of the first turret tool post and second turret tool post, to the back attachment in a direction of Z axis, and provided with tool holding portions in at least two rows and two lines in directions of X axis and Y axis.