In the Belt Conveying Laboratory (LTT) at the Faculty of Geoengineering, Mining and Geology at Wroclaw University of Technology a new area of application has been found for the newly developed high resolution magnetic diagnostic device for assessment of steel cord conveyor belts condition. In addition to monitoring of belts during their operation on conveyors this device can be used in LTT as the new tool in belts resistance to puncture investigations. High resolution images of changes in magnetic field of magnetized cord wires can be used for evaluation of failures and cuts caused by dynamic impact of iron head (striker) during laboratory tests without belt cover removal. The usefulness of the device is even greater due to not only condition of steel cord belts can be evaluated, what for this device was developed, but it allows also on observations of failures in impact-resistant metal breakers in textile belts. Breakers are frequently made of thin wires vulcanized above carcass inside the top cover laterally to the center line of the belt. The aim of breakers is protection of the expensive core against failures caused by big lumps of rock with sharp edges falling onto belt surface in loading points. Their role is shock absorption to minimize gouging and resistance of longitudinal rips. Due to breaker wires can also be magnetized after changing the direction of samples of punctured belts they can be monitored using the developed device at the testing conveyor. In the paper the first outcomes of application of magnetic diagnostic device for evaluation of punctured steel cord belts and textile belts with metal breakers are presented.