The radiation mechanism of electromagnetic noise from an LED lamp and its impact on communication quality of digital terrestrial television broadcasting (DTTB) are investigated. The impulses of the electromagnetic noise from the LED lamp are observed and synchronized to the light-dark changes in the light emission which is controlled by the switching regulator of the LED lamp. The switching regulator of the LED lamp is the source of the outbreak of the LED noise. Then, the distribution of current on the lighting duct rail is measured. The LED noise is flowing on the lighting duct rail. This noise is generated in the LED lamp and radiated to the free space through the lighting duct rail of the LED lighting system. Furthermore, the communication quality of DTTB subjected to the LED noise is evaluated by the amplitude probability distribution (APD). Measuring APD of the LED noise is a useful method to evaluate the characteristics of the LED noise. The tolerance level of the LED noise for the reception of the DTTB signal is estimated from the APD curve of the LED noise.