Door open monitoring for an intelligent device is disclosed. In a method for monitoring a door of an intelligent device according to an exemplary embodiment of the present disclosure, it is decided whether to send a message relating to the ventilation of the inside of a drum by analyzing an image generated through a camera placed in the door. A door monitoring system of the present disclosure may be associated with an artificial intelligent module, an unmanned aerial vehicle (UAV), a robot, an augmented reality (AR) device, a virtual reality (VR) device, a 5G service-related device, etc.