In a method for downloading data through a multimedia device, a screen output device generates a multimedia output representing data to be downloaded through the multimedia device. An analog level comparator compares a level of an electric signal with a reference level, i.e., a reference voltage, and outputs a comparison result signal. A digital signal input device receives the comparison result signal from the comparator. An error correcting section judges whether the downloaded data is damaged based on the comparison result signal from the comparator. If the error is detected, the reference voltage of the analog level comparator is amended, so as to accurately control sensitivity until the error is absent. If the error is not detected, the downloaded data is used.