Abstract: A machine tool includes a spindle head (4) movable in a predetermined direction, a spindle (9) attached to the spindle head (4) for undergoing machining of a workpiece, a column (3) supporting the spindle head (4), the column (3) being movable over a predetermined plane (X-Y plane) perpendicular to the predetermined direction so that the spindle head (4) is movable over a plurality of machining regions (22L, 22R), a plurality of palettes (23L, 23R) each detachably mounting the workpiece and movable into and away from its associated machining region, and a table (13) mounting the plurality of palettes (23L, 23R) thereon. In one aspect of the invention, an external operation box (101) is provided from which a selected program number is entered and is impressed on an input port of a CPU (100). The CPU (100) calls a machining program identified by the selected program number to thus perform machining of the palette loaded on the associated machining region.