PURPOSE: To dissolve the shortage of the number of tools of an opposed spindle lathe and the like to simultaneously work both sides of a work.

CONSTITUTION: A multicutter rotary tool holder 18 provided with a rotary tool spindle 28 capable of being mounted with tools TA and TB on both ends, a turning body 22 having a drive shaft 25 perpendicular to the tool spindle 28, and a holder main body supporting the turning body capably of being turned and indexed by 180° around the drive shaft axis, is detachably mounted on a first turret 12 or a second turret 15. The turning body is turned by 180° by means of a indexing drive unit provided on a first tool rest or a second tool rest, and alternately indexed so that the tools mounted on both ends of the rotary tool spindle facing in the direction of Z-axis are faced to the work side.