To provide a machine tool for performing automatic unmanned operation for a long time even in the case of the tool being worn during continuously machining a workpiece.

A two-spindle-type combined machining lathe comprises a first spindle head 12 fixedly installed at one end of a bed and a second spindle head 13 opposed to the first spindle head 12 and installed at the other end of the bed movably toward a Z-axis, wherein a turret 14 and a column 16 to be moved on the bed toward the Z-axis are installed between the first spindle head 12 and the second spindle head 13 and a tool spindle head 18 is supported on the inclined surface of the column 16 via a supporting base 17 to be moved toward a X-axis turnably to a B-axis. A grinding attachment 20 having a rotary grinding wheel 21 for grinding the tool and a driving mechanism 22 for the rotary grinding wheel 21 is fixedly installed at the upper part of the first spindle head 12 so that the tool mounted on the tool spindle head 18 can be automatically reground.