To provide a machine tool, particularly a machining center for machining work by drilling, lathing, milling, polishing, etc., and to increase the rigidity of the machine tool, particularly the rigidity of a member bearing a machining spindle.

In the machine tool, a rotatable machining spindle 8 is arranged in a slider between guides in an X direction, and axially borne on two side surfaces disposed in a mutually facing manner. The combination of a vertical slider 6 having flexural rigidity with guide tracks 2, 2' provided for the machining spindle 8 on both sides thereof produces a particularly short and symmetrical flux line as a result, to thereby obtain high static and dynamic rigidity.