Cannabis, presently being one of the most commonly employed psychoactive agents globally, ranks after alcohol and nicotine. Despite the permissibility of employing cannabis for medicinal objectives in Korea, the discussion regarding the authorization and control of cannabis for both recreational and medicinal intentions persists, giving rise to apprehensions about the plausible hazards and repercussions of cannabis on public well-being and health. Cannabis has the potential to induce positive experiences that mitigate certain psychiatric symptoms depending on the individual. However, a multitude of studies have demonstrated a close association between cannabis usage and detrimental effects on the brain, including the onset of schizophrenia and the deterioration of cognitive function. The endocannabinoid (eCB) system, which serves as the primary target for the active components of cannabis, was only recently discovered, and the precise mechanisms through which the intricate substances within cannabis interact with the body remain inadequately comprehended. The use of medical cannabis for mental illness has shown promise in treating anxiety, post-traumatic stress disorder, sleep disorders, and substance use disorders. Recent research has focused on the discovery of the eCB system, which plays a role in the therapeutic effects of cannabinoids. These studies are advancing the development of new treatments for mental disorders through research and clinical trials. In conclusion, while cannabis-related substances carry a risk for mental health, the eCB system also holds potential as a new therapeutic mechanism. Further research is needed to better understand the mechanisms of cannabinoids and determine appropriate medical uses.