A wire electrical discharge machine includes: a mounting table having a placement plane on which a workpiece can be placed; a first guide portion and a second guide portion for stretching a wire electrode therebetween. The first guide portion is integrally equipped with a probe. The relative position in the placement plane between the probe detecting its abutment with the workpiece and the first guide portion before moving the relative position between the first guide portion and the second guide portion is stored as an offset. This offset is corrected based on the tilt information indicating the tilt state of the workpiece relative to the placement plane. Thus, it is possible to obtain the corrected offset in accordance with the tilt state of the workpiece after changing the relative position between the first guide portion and the second guide portion.

In wire-electrical discharge machine and a numerical control apparatus thereof and a numerical control apparatus for controlling a machine tool, optional minute blocks are automatically created in front of and behind a connecting point, i.e., a joint of a block to which an offset command is instructed, and an offset value is exchanged between the minute blocks so that a correct offset value is set in a desired block.

In wire-electrical discharge machine and a numerical control apparatus thereof and a numerical control apparatus for controlling a machine tool, optional minute blocks are automatically created in front of and behind a connecting point, i.e., a joint of a block to which an offset command is instructed, and an offset value is exchanged between the minute blocks so that a correct offset value is set in a desired block.