To quickly stabilize the tension of a web, to reduce spoilage, and thereby to improve economics.

In an operating method of a printing machine provided with a plurality of rollers on the course of the web 7, the web 7 is conveyed by these rollers, on which printing is made by printing cylinders, at least one of rollers having an effect on the tension of the web 7, out of those provided on the course of the web 7, is put in a contact with the web 7, while the printing cylinders are out of contact, and a tension applying operation for increasing the tension of the web is conducted. After this operation, the web is accelerated to keep ready for printing.