Abstract: Threading apparatus in a rotary printing press for threading the web through the turning bar. An endless double threading belt is provided along the path of the web through the turning bar. The double threading belt comprises two belts engaged with each other. The web is slit lengthwise into a wider web and narrower web by a slitter located before the turning bar. A side edge of the wider web is nipped in the double threading belt and pulled through the turning bar by the double threading belt during the threading operation so that threading of the wider web through the turning bar is accomplished. After threading the wider web is cut free from the double threading belt. After completion of threading the following full web is cut into equal widths by a slitter. The double threading belt is separated into two belts after threading so that the nipped side edge is removed from the this belt.