Abnormality detection device of machine tool

An abnormality detection device of a machine tool including a spindle that rotates a tool or a work and a feed axis that moves the tool or the work, comprising:

• a load monitoring unit that monitors a load of at least one of the spindle and the feed axis;
• an abnormality detection unit that detects an abnormality in the machine tool when the load of at least one of the spindle and the feed axis monitored by the load monitoring unit is equal to or larger than a threshold;
• a storage unit that stores shape data of the work and shape data of the tool in advance;
• a non-machining area or machining area calculation unit that calculates at least one of a non-machining area in which the tool does not interfere with the work and a machining area in which the tool interferes with the work on the basis of the shape data of the work and the shape data of the tool;
• and
• a threshold changing unit that changes a threshold of abnormality detection in the non-machining area to a value lower than a threshold of abnormality detection in the machining area or changes a threshold of abnormality detection in the machining area to a value higher than a threshold of abnormality detection in the non-machining area.