An apparatus and method for data interface of a flat panel display device, which is capable of transferring clocks in a state, in which the clocks are embedded in digital data, thereby reducing the number of transfer lines, is disclosed. The apparatus includes a transmitter unit built in a timing controller, to transmit transfer data with an embedding clock embedded between successive pieces of data, and a clock enable signal to indicate the embedding clock, and receiver units respectively built in a plurality of data integrated circuits connected to the timing controller, to separate and detect the embedding clock and the data from the transfer data, in response to the clock enable signal.