A machine tool comprising one or plural storage magazines which are mounted along the vertical direction rotatably around a vertical axis on an upstanding support frame structure at a side of working station. Each of the magazines stores at the periphery thereof a plurality of spindle heads, workpiece supporting jigs or tool supporting heads which are alternatively set one by one to a set position at the working station for operation on workpieces. Alternative setting of such heads or jigs is achieved by a selective rotation of each magazine and by a selective lifting and lowering of the head or jig between the set position and a store position just above such set position. Floor space required for storing and exchanging the heads or jigs is largely saved. A particular exchanging device for exchanging heads or jigs stored by the magazines for another heads or jigs is provided which greatly enlarges processings possibly carried out at the working station.