To provide a perforation forming device capable of forming a pair of skip perforations having different shapes from each other along the longitudinal direction of a continuous paper sheet.

The device is provided with a first laser beam source 11 which pulse-oscillates a laser beam for forming first perforations, a second laser beam source 21 which pulse-oscillates a laser beam for forming second perforations, a first beam conductive part 16 for conducting the laser beam outputted from the first laser beam source to the sheet, and a second beam conductive part 26 for conducting the laser beam outputted from the second laser beam source to the sheet. The time outputting characteristic of the first laser beam source and the time outputting characteristic of the second laser beam source are controlled independently from each other.