A numerically controlled lathe (10) includes a control unit (24) for controlling the operations of at least one spindle (14, 16) and at least one tool rest (18, 20) on a lathe bed (12) along a plurality of control axes in a plurality of lines. The control unit (24) has an input section (100) for inputting a plurality of machining programs about a plurality of tools (22) mounted on at least one tool rest, a storage section (112) having a plurality of program-describing areas ($1, $2, $3) corresponding to the lines for describing and storing the machining programs input by the input section in the program-describing areas, and a processing section (116) for allocating the control axes to the program-describing areas in the storage section, each control axes being as a reference control axis, and for applying, to an actual control axis for controlling a machining operation relating to one designated tool designated in each machining program, the reference control axis allocated to a program-describing area freely selected from the program-describing areas to describe a machining program designating the designated tool.