To provide a turret tool rest for a vertical lathe preventing a turret head from falling downward even in power failure.

A hydraulic index device 10 provided with oil pressure supply parts 125, 127 for selectively supplying pressure oil to hydraulic chambers 105a, 105b is provided to push a turret head 111 upward by pressure oil supplied to the hydraulic chamber 105a, so as to regulate its rotation by a clamp means, and to push the turret head 11 downward by pressure oil supplied to the hydraulic chamber 105b, so as to released regulation to rotation by the clamp means. A check valve 11 with its pilot part 12 connected to a flow passage 129 to supply pressure oil to the hydraulic chamber 105b is provided in a flow passage 128 for supplying pressure oil to the hydraulic chamber 105a. Back flow of pressure oil in the hydraulic chamber 105a is thus prohibited by the check valve 11, thereby fall of the turret head 111 is prevented.