The utility model relates to a monitoring devices that is used for elevator dimension guarantor to supervise automatically compares with prior art and has solved the defect that elevator dimension guarantor is difficult to automatic supervision. The utility model discloses a current transformer, elevator controller's IO port and safety loop's interconnecting link pass current transformer's annular magnetic core, and current transformer is located elevator controller and overhauls between the switch, and current transformer's signal output part and elevator controller 0's elevator controller 1 link to each other. The utility model discloses a with elevator control system's non - contact, thus indirect the detection overhaul the on off state and confirm whether the elevator ties up the guarantor, do not produce any influence to original elevator control system, and the implementation process is convenient reliable.