The present invention relates to an elevator condition monitoring system, which comprises at least a control unit (104) and a sensor arrangement (250) connected to the control unit, while the elevator comprises an elevator car (100), an elevator drive machine (109) and a control system (110) including the required safety circuit and actuators. The control unit of the condition monitoring system and the sensor arrangement connected to the control unit have been fitted in conjunction with the elevator car. The sensor arrangement comprises at least a sensor which measures the current of the safety circuit and is galvanically separated from the elevator safety circuit and connected to the safety circuit without interrupting the safety circuit wiring.