Various embodiments of the present invention relate to an apparatus and a method for transmitting data between internal modules in an electronic device. Here, a transmission apparatus of a digital interface may comprise: multiple transmission lines connected to a reception apparatus; and multiple transmission circuits connected in parallel to each other and provided for each of the transmission lines, wherein the transmission apparatus may be configured to transmit data having different voltages to the reception apparatus, using at least one transmission circuit among the multiple transmission circuits for each of the transmission lines on the basis of a variation of the voltage of data to be transmitted through each of the transmission lines. Other embodiments are also possible.