Collapses of Masonry structures such as stone lanterns and bridge railings due to earthquakes and to deterioration have been reported. Some of them are to be repaired without changing their original appearance as heritage structures. Bonded anchor may be one possible solution to these problems, but design criteria for bonded anchor have not yet been established in Japan. In this paper, pull-out tests were conducted to investigate the mechanical behaviour of stones strengthened with bonded anchors. The results showed that the depth of embedment length of the anchors greatly affected a combined cone failure and pull-out failure, and that the pull-out failure surface varied depending on the uniaxial compressive strength of the stone. It was also suggested that the ultimate resistance formula derived from the experimental results can estimate their maximum load and failure mode with more accuracy than calculation formula in the guideline used for concrete structures.