Misalignment detection device and misalignment detection method

A misalignment detection device that detects a misalignment of a center axis with respect to an axis of rotation when a workpiece having such an outer peripheral shape that a distance in a radial direction from the center axis to an outer peripheral part repeatedly increases and decreases in a circumferential direction rotates about the axis of rotation, the device comprising:

• a storage that stores a reference pattern corresponding to a part of the outer peripheral part;
• an imager that images the outer peripheral part at least for one turn of the workpiece by such imaging at a fixed point as to include at least a part of the outer peripheral part in an imaging field of view;
• an image processor that detects a region corresponding to the reference pattern by performing a pattern matching process for an image captured by the imager;
• and
• a misalignment detector that detects the misalignment based on information on a position of each of a plurality of the detected regions, wherein
• the reference pattern corresponds in shape to a plurality of characteristic parts that present on the outer peripheral part, have shapes congruent to each other and have a mutually symmetrical positional relationship with respect to rotation about the center axis.