To provide a combined machining apparatus and a combined machining method for combiningly performing waterjet machining and wire cut discharge machining, which is adapted to reduce machining time of the entire combined machining by precisely performing the waterjet machining.

The combined machining apparatus has a workpiece cut width computing means 234 for computing a cut width of a workpiece W corresponding to a change in the movement speed of a jet nozzle 2 based on the correlation between the movement speed of the jet nozzle 2 and the cut width of the workpiece W; a waterjet machining execution means 237 for executing waterjet machining by moving the jet nozzle 2 on a moving path based on the cut width of the workpiece W computed by the workpiece cut width computing means 234; and a wire cut discharge machining execution means 238 for executing wire cut discharge machining after the waterjet machining is executed by the waterjet machining execution means 237.