Measuring instrument

Measuring instrument for measuring a swinging movement of an arm (220) having a stylus (222D) contacting a workpiece (1). Centroid moments of components of the arm (220) are calculated based on three-dimensional model data and mass of the components, the centroid moments being combined to calculate a centroid position (G) of the entirety of the arm (220). The arm (220) is adjusted and swingably supported so that the stylus (222D), provided on an end of the arm (220) being swingably supported by a support (210) that moves relative to a workpiece (1), touches the workpiece (1) with a predetermined measuring force and the centroid position (G) is located on a horizontal plane including the fulcrum when the support (210) is inclined by an angle in the middle of an angle range within which the support (210) is rotated by a moving section (130). The measuring force is hardly fluctuated when the support (210) is inclined.