It is hard to protect the copyright of the medical images by the Copyright Act because the medical images have the digital property. Especially, if people copy the medical image, another original one will be created. Thus, people send the original medical image to the others unconsciously. After all, it can not dispute about who made the image for the first time. Nowadays, the medical environment has been changed to the digital environment rapidly. So, the study on the security of the medical image is needed. In this paper, we search the significant problems of the part and we research the security of the medical image using the watermark for addressing the problems. However, we could know that our study has the limitation of the legal certification because we could not guarantee about the integrity that is the important feature of the medical images.