A medical device having an operation input unit for an operator to enter instructions and a operation unit for performing prescribed operations required for medical treatment based on input from said operation input unit, including a dialysis device that purifies patient's blood by means of extracorporeal circulation. Further having a human body detection unit for detecting the operator's presence in the vicinity of operation input unit, and a control unit that provides control for allowing input operation unit to instruct the operation unit's operations, or allowing the operation unit to operate based on the input entered into operation input unit, only when said human body detection unit is detecting the operator.