Device for machining of an in elongate workpiece that is to be machined, comprising: a milling tool and a steady rest for supporting an elongate workpiece that is to be mechanically processed, in particular machined, wherein the steady rest comprises: a steady rest main body that can be arranged in the device, at least one two means (4, 5) that are arranged or formed on the steady rest main body and each intended for supporting a workpiece that is to be mechanically machined, which support means each comprises at least one support element (6, 7) that supports a workpiece that is to be supported, wherein the support means (4, 5) each are a clamping or gripping means or comprise same and the at least one support element is a clamping or gripping element or comprises same; wherein the support means (4, 5) are each arranged or formed on the steady rest main body so as to be movable, relative to the steady rest main body, in at least one degree of freedom of movement that defines a movement path (B1, B2), characterized in that the support means (4, 5) are each mounted so as to be movable between an operating position in which support for a workpiece to be supported takes place, wherein the support means (4, 5) are clamped or gripped against the workpiece to be supported, and a non-operating position in which support of a workpiece to be supported does not take place; wherein in the operating position of the support means (4, 5), a possibility for a passage is provided for the milling tool to pass through the steady rest, such that the milling tool can move along the longitudinal axis of a workpiece that is supported by the steady rest and is to be machined via the possibility for a passage in the direction of the longitudinal axis of the workpiece that is to be machined. a steady rest main body that can be arranged in the device, at least one two means (4, 5) that are arranged or formed on the steady rest main body and each intended for supporting a workpiece that is to be mechanically machined, which support means each comprises at least one support element (6, 7) that supports a workpiece that is to be supported, wherein the support means (4, 5) each are a clamping or gripping means or comprise same and the at least one support element is a clamping or gripping element or comprises same; wherein the support means (4, 5) are each arranged or formed on the steady rest main body so as to be movable, relative to the steady rest main body, in at least one degree of freedom of movement that defines a movement path (B1, B2), characterized in that the support means (4, 5) are each mounted so as to be movable between an operating position in which support for a workpiece to be supported takes place, wherein the support means (4, 5) are clamped or gripped against the workpiece to be supported, and a non-operating position in which support of a workpiece to be supported does not take place; wherein in the operating position of the support means (4, 5), a possibility for a passage is provided for the milling tool to pass through the steady rest, such that the milling tool can move along the longitudinal axis of a workpiece that is supported by the steady rest and is to be machined via the possibility for a passage in the direction of the longitudinal axis of the workpiece that is to be machined.