A monitoring system for monitoring the conditions of a band circulating in a paper-making machine, comprises a guide extending substantially along an axis; and a monitoring apparatus movable along the guide and comprising at least one measuring device configured to measure at least one parameter indicative of the conditions of the band; the apparatus is a self-propelled motorized apparatus, provided with a motor and at least one driving member operated by the motor and which engages at least one corresponding surface of the guide to move the apparatus along the guide.