The present invention relates to a machining system etc. capable of highly accurately machining a workpiece even in a case where the workpiece is deflected. A machining system 1 is configured with a lathe 10 having end portion supporting mechanisms 13, 15 for supporting both end portions of an elongated workpiece W horizontally, a tool rest 20 for holding a tool, a feed mechanism for moving the tool rest 20 in three orthogonal directions, and a control device 25 for controlling the feed mechanism, and a non-contact measuring device 30 for measuring the deflection shape of the workpiece W when the workpiece W is rotated. The control device 25 moves the tool along the deflection shape measured by the non-contact measuring device 30.