The invention relates to a machine tool (1), comprising: a separating device (4) for dividing a working space (3) into a machining area (5) for machining a workpiece (18) and into at least one further working area (6), a machining head, in particular a laser machining head (8), for machining the workpiece (18) in the machining area (5), a rotary workpiece changer (10) having a rotatable workpiece support (9) for transporting the workpiece (18) between the machining area (5) and the at least one further working area (6) through an opening (16) formed in the separating device (4), wherein the rotatable workpiece support (9) has a protective wall (12), in order to shield the at least one further working area (6) from the machining area (5) during the machining of the workpiece (18). The separating device (4) has a protective element (17), which is movable between a machining position (BS) and a transport position, wherein, in the machining position (BS), the protective element (17) rests against the protective wall (12) in order to close the opening (16), wherein, in the transport position, the protective element (17) is spaced apart from the protective wall (12), and wherein a distance (A) between the machining position (BS) and the transport position (TS) of the protective element (17) is settable in a manner depending on the dimensions of the workpiece (18). The invention also relates to an associated method for machining a workpiece (18).