A waistband for an absorbent article having a waistband with differential extensibility andor contraction along the circumference of the waist opening. The device further includes a beam splitting element, and the controller adjusts a deflection amount of the laser beam from the electro-optic element based on a detection result by the positional shift detecting unit and corrects a positional shift in the sub-scanning direction of the laser beam on the scan-target surface. An in-plane retardation value of the first biaxial retardation film at a wavelength of 550 nm is Ro1.