Abstract: In order to provide a method of detecting seam characteristic points which makes it possible to accurately and quickly detect seam characteristic points, which are used as work target positions, by using coordinate data of a series of distance points detected by a sensor, when sealing is performed by a robot (1) equipped with a sensor (2), seam characteristic points P of an object are detected, a distance to an arbitrary cross section of an object is detected by the sensor (2), the data obtained through the measurement are converted into coordinate data of a series of distance points arranged in a predetermined order, a statistic value regarding the distance between paired adjacent distance points among the series of distant points is calculated so as to obtain a threshold level for judging discontinuity, based on the statistic value, the distance between paired adjacent distance points is compared with the discontinuity threshold level so as to detect a pair of adjacent distance points which are separated fr