Abstract: A button indexing device used in a button attaching machine for attaching a button to be indexed in a specific orientation on a fabric of garments or the like, including lower mold provided at a button attaching position of the attaching machine, a driving section for turning the lower mold around a vertical axis, a laser beam source for irradiating a laser beam onto a point of a specified circular track of the button to be held in the lower mold around the vertical axis, an optical sensor for detecting light reflected from or scattered by the button, and a stop section for stopping said lower mold in a rotation position capable of obtaining the right orientation when said optical sensor detects the minimum or maximum amplitude.