Abstract: A robotic system for inspecting the safety status of bridges is proposed in this paper. Currently, most bridge inspections have been done manually by counting the number of cracks, measuring their lengths and widths and taking pictures of them. Thus the quality and reliability of diagnosis reports on bridges are greatly dependent upon the diligence and education of inspection workers. The robotic inspection system to be proposed consists of three parts: a specially designed car, a robot mechanism and control system for mobility and a machine vision system for automatic detection of cracks. Ultimately, this robot system has been developed for gathering accurate data in order to record the biennial changes of the bridge's safety circumstances as well as check the safety status of bridges. We also demonstrate the effectiveness of the suggested crack detecting and tracing algorithms through experiments on a real bridge crack inspection.