An interference determination method for machine tools which determines whether or not there will be interference between elements that move relative to each other, the method including: a setting procedure for setting a machine tool model obtained by combining the shape model of each of the elements including a work model corresponding to the work; a measurement procedure for measuring the position of the work attached to the work attachment part; a correction procedure for acquiring, at a predetermined timing, the position of the work measured in the measurement procedure, and correcting the machine tool model set in the setting procedure; and a determination procedure for determining whether or not there will be interference between the elements on the basis of the machine tool model corrected in the correction procedure.