Abstract: In the method for monitoring a paper web or the like, the properties and state of the paper web (W) or the like, travelling in a paper machine or in a finishing machine for paper are monitored by observing the travelling paper web with one or more image-forming systems based on camera technique, and the properties of the web are measured with a system comprising one or more physical on-line measurement methods. The systems use different observation devices for monitoring the web. At least two different systems, which use different observation devices, are integrated at least partly by placing the web observation devices in the same machine part, by using software of different systems on the same substation (8), and/or by using the same user interface software for both systems in the workstation (9) in the user interface. The observation devices of different systems can be cameras (2) and sensors, which are placed in the same measurement beam or frame (1) extending across the web (W).