The depression is very much disease in today. When glancing, it has nothing to do with ED, but actually ED has a big relation to the depression. As I previously wrote that the cause of ED included an oxidation stress or social stress. In fact, these two stresses can be causes of the depression, too. The oxidation stress reduces nitric-monoxide (NO), but NO doesn’t only play an important role for the vascular dilatation in penis, but also has an important role with the communication of the nerve cell. Therefore the decrease of NO doesn’t only cause of decline of the bloodstream but also affect on nervous communication. This communication disorder causes the depression. Also, the social stress activates a sympathetic nerve and makes a tension state to continue. With this, the escape-behavior as the mental defense occurs and this can be another cause of the depression. There is a research data in America, saying that about 10 percent of the ED patients were actually suffering from depression. A deep correlation between ED and depression is actually seen from this report. The basic treatment of the depression includes prescribing of anti-depression medicine, however the anti-depression medicine actually has an effect which increases NO, too. As the ED curatives, such as Viagra, Levitra and Cialis and so on, also has an effect to promote NO production, there is actually a common point between anti-depression medicine and the ED curatives. It is unexpected relation between the depression and ED, whichever the early treatment is necessary as the both of these are serious clinical condition.