A machine tool comprising: fixtures (12a,12b) for holding a workpiece extending in a longitudinal direction and in a width direction and having a flat surface (Wa) and a curved surface (Wb) opposed to the flat surface (Wa) with the flat surface (Wa) disposed horizontally; a pair of first beds (21a,21b) spaced in the width direction and extending in the longitudinal direction corresponding to a horizontal X axis direction and having guide surfaces (41a,41b) inclined at a second angle (β) with respect to the horizontal X axis direction so as to extend in an inclined X axis direction; a pair of moving members (22a,22b) supported on the guide surfaces (41a,41b) of the first beds (21a,21b) so as to be movable in the inclined X axis direction; a first cross rail extending in the width direction and laid between upper ends of the moving members (22a,22b) so as to be movable in the inclined X axis direction via the movement of the moving members (22a,22b), wherein the first cross rail supports a first saddle in such a way that the first saddle is movable on a guide surface of the cross rail, and wherein the first cross rail can be inclined at a first angle (α) with respect to the horizontal Y axis direction in that the height of one of the moving members (22a,22b) is arranged to be set lower than the height of the other moving member (22a,22b), thereby inclining the moving direction of the first saddle on the guide surface of the cross rail in an inclined Y axis direction orthogonal to the horizontal X axis direction and the inclined X axis direction; and a first machining head to which a first rotary tool configured to perform machining on the curved surface (Wb) of the workpiece held by the fixtures (12a,12b) is rotatably attached, wherein the first saddle is configured to move the first machining head in an axis direction of the first rotary tool. fixtures (12a,12b) for holding a workpiece extending in a longitudinal direction and in a width direction and having a flat surface (Wa) and a curved surface (Wb) opposed to the flat surface (Wa) with the flat surface (Wa) disposed horizontally; a pair of first beds (21a,21b) spaced in the width direction and extending in the longitudinal direction corresponding to a horizontal X axis direction and having guide surfaces (41a,41b) inclined at a second angle (β) with respect to the horizontal X axis direction so as to extend in an inclined X axis direction; a pair of moving members (22a,22b) supported on the guide surfaces (41a,41b) of the first beds (21a,21b) so as to be movable in the inclined X axis direction; a first cross rail extending in the width direction and laid between upper ends of the moving members (22a,22b) so as to be movable in the inclined X axis direction via the movement of the moving members (22a,22b), wherein the first cross rail supports a first saddle in such a way that the first saddle is movable on a guide surface of the cross rail, and wherein the first cross rail can be inclined at a first angle (α) with respect to the horizontal Y axis direction in that the height of one of the moving members (22a,22b) is arranged to be set lower than the height of the other moving member (22a,22b), thereby inclining the moving direction of the first saddle on the guide surface of the cross rail in an inclined Y axis direction orthogonal to the horizontal X axis direction and the inclined X axis direction; and wherein the first cross rail supports a first saddle in such a way that the first saddle is movable on a guide surface of the cross rail, and wherein the first cross rail can be inclined at a first angle (α) with respect to the horizontal Y axis direction in that the height of one of the moving members (22a,22b) is arranged to be set lower than the height of the other moving member (22a,22b), thereby inclining the moving direction of the first saddle on the guide surface of the cross rail in an inclined Y axis direction orthogonal to the horizontal X axis direction and the inclined X axis direction; and a first machining head to which a first rotary tool configured to perform machining on the curved surface (Wb) of the workpiece held by the fixtures (12a,12b) is rotatably attached, wherein the first saddle is configured to move the first machining head in an axis direction of the first rotary tool.