To provide a work reversing device reversing work without limiting moving action of one head-stock even when the other head-stock moves to a work giving/receiving position, and without increasing the total horizontal size of a machining tool, in a main spindle traveling type vertical machining tool having the two head-stocks.

This work reversing device 3 of a spindle traveling type vertical lathe 1 comprises a reversing device base body 50 arranged at a generally center position in an X-axis direction between a first machining area 20 and a second machining area 23, a reversing device side holding portion capable of gripping and releasing work 8, a reversing means generally 180°C reversing the work, and a moving means moving the reversing device side holding portion between a generally horizontal first position in the first machining area 20 giving the work to and receiving it/from a first chuck 15 of a first spindle 9 and a generally horizontal second position in the machining area 23 giving the work to and receiving it/from a second chuck 16 of a second spindle 10.