Human brain can be stimulated safely and non invasively by powerful magnetic field. This magnetic field causes a current in stimulated tissue, which stimulates the brain neurons. In psychological disorders, focal brain activity is observed in clinical syndromes. Application of trans-cranial magnetic stimulation as a therapeutic technique proposes to change the selective brain activities. Low frequency repetitive trans-cranial magnetic stimulation (rTMS) is a new method in evaluation and treatment of hyper excitability brain syndromes, which changes brain plasticity. In this review article, therapeutic effect of rTMS in some psychological disease such as depression, post traumatic stress disorder, epilepsy, obsessive compulsive disorder and schizophrenia is discussed.