A turret (11) is clamped to a tool rest main body (10) by a pair of coupling members (27). During indexing rotation for selecting a tool, the tool rest main body (10) and the turret (11) are moved relatively in a Z-axis direction, and the pair of coupling members (27) are unclamped. At this time, the tool rest main body (10) is moved in the Z-axis direction relative to a lathe main body (100) in synchronization with the relative movement in the Z-axis direction between the tool rest main body (10) and the turret (11). This movement of the tool rest main body (10) is adjusted in direction and moving distance so that the relative movement between the turret (11) and a spindle table (1) is eliminated. As a result of this movement control, the turret (11) and the tool fitted to the former do not have relative displacement to the spindle table (1) and to a work, so that the danger of mutual interference among these constituent elements and the work can be eliminated.