Drugs medicated for elderly patients show different pharmacokinetics from young patients, because of change in the makeup of bodies, decrease of albumin, increase of alpha-1-acid glycoprotein, hypofunction of metabolism, and excretion by aging. In addition, complications or other concomitant drugs influence their pharmacokinetics. Therefore, when we take medication for elderly patients, we need consideration different from young patients. Psychiatric symptoms which frequently occurred in elderly patients are dementia (including behavioral and psychological symptoms of dementia), depressive state, sleep disturbance, and delirium. As warned by Food and Drug Administration, some studies reported that using antipsychotics for elderly patients with dementia increase their death rate. We have to give informed consent sufficiently to patients and their families.