Provided is a device for controlling a wire electrical discharge machining apparatus, the device making it possible to improve machining precision even in machining in which a plurality of corner control segments overlap. A device for controlling a wire electrical discharge machining apparatus, the device comprising: a storage unit that stores a machining program and a prescribed plurality of corner control patterns that can be applied to each corner part; a control unit that performs corner control for switching between prescribed machining conditions on the basis of a corner shape during machining of a corner part; a calculation unit that calculates a corner control segment from the start point and the end point of the corner control; and a selection unit that, when the corner control segments calculated by the calculation unit overlap, selects one corner control pattern to perform in a prioritized manner from the storage unit.