A method for controlling a machine tool in which a work mounted on a table is machined through relative movement in X, Y and Z axis directions between the table and a main spindle, characterized by the following steps: a step of measuring coordinate values in X and Y axis directions of a measuring tool that has an interrupting portion shaped as a circular cone form and is attached to the main spindle at a first time through performing the following substeps of: - irradiating laser beam from an emitting element towards an photosensitive element provided on the table respectively, - interrupting the laser beam by making the measuring tool move relative to the laser beam in a first direction to cross the laser beam through a relative movement between the main spindle and the table, - interrupting the laser beam by making the measuring tool move relative to the laser beam in the direction opposite to the first direction to cross the laser beam through a relative movement between the main spindle and the table, - delivering detection signal of interruption when the measuring tool has interrupted the laser beam, and - obtaining coordinate values of the measuring tool in X and Y axis directions for respective directions of interruption based on the delivered detection signal of interruption, a step of measuring coordinate values in X and Y axis directions of the measuring tool at a second time after an interval of time from the first time through performing the same substeps as at the first time, a step of obtaining the distance in the direction normal to the laser beam between the coordinate values measured at the first time and the distance in the direction normal to the laser beam between the coordinate values measured at the second time through processing the differences of the coordinate values measured with interruption of the laser beam at the first time and at the second time respectively, a step of obtaining displacement value in Z axis direction between the main spindle and the table over the first time and the second time by use of the shape of the interrupting portion of the measuring tool, and a step of controlling the machine tool through correcting the position based on the obtained data. a step of measuring coordinate values in X and Y axis directions of a measuring tool that has an interrupting portion shaped as a circular cone form and is attached to the main spindle at a first time through performing the following substeps of: - irradiating laser beam from an emitting element towards an photosensitive element provided on the table respectively, - interrupting the laser beam by making the measuring tool move relative to the laser beam in a first direction to cross the laser beam through a relative movement between the main spindle and the table, - interrupting the laser beam by making the measuring tool move relative to the laser beam in the direction opposite to the first direction to cross the laser beam through a relative movement between the main spindle and the table, - delivering detection signal of interruption when the measuring tool has interrupted the laser beam, and - obtaining coordinate values of the measuring tool in X and Y axis directions for respective directions of interruption based on the delivered detection signal of interruption, - irradiating laser beam from an emitting element towards an photosensitive element provided on the table respectively, - interrupting the laser beam by making the measuring tool move relative to the laser beam in a first direction to cross the laser beam through a relative movement between the main spindle and the table, - interrupting the laser beam by making the measuring tool move relative to the laser beam in the direction opposite to the first direction to cross the laser beam through a relative movement between the main spindle and the table, - delivering detection signal of interruption when the measuring tool has interrupted the laser beam, and - obtaining coordinate values of the measuring tool in X and Y axis directions for respective directions of interruption based on the delivered detection signal of interruption, a step of measuring coordinate values in X and Y axis directions of the measuring tool at a second time after an interval of time from the first time through performing the same substeps as at the first time, a step of obtaining the distance in the direction normal to the laser beam between the coordinate values measured at the first time and the distance in the direction normal to the laser beam between the coordinate values measured at the second time through processing the differences of the coordinate values measured with interruption of the laser beam at the first time and at the second time respectively, a step of obtaining displacement value in Z axis direction between the main spindle and the table over the first time and the second time by use of the shape of the interrupting portion of the measuring tool, and a step of controlling the machine tool through correcting the position based on the obtained data.