A printing system has a first printer apparatus for forming an image on a first plane of a web having no feed holes and a second printer apparatus provided at a post stage following the first printer apparatus for forming an image on a second plane of said web. The first printer apparatus (P1) is operable to form a position-alignment mark (Rm) at a predesignated position on each page of a web. This position-alignment mark is detected by mark detection means of the second printer apparatus (P2). Control means is provided for controlling the web transport speed so that both the generation timing of a web feed control signal (CPF-N signal) being generated with preset cyclic periods and the generation timing of a mark detection signal issued from the mark detection means through detection of the position-alignment mark are kept constant in phase.