Disclosed is a data transmitting circuit and a method based on a differential value data encoding to reduce a data transmitting time by transmitting an encoded differential value. The circuit comprises an encoder for encoding and outputting a differential value between a currently transmitted data value and a previously transmitted data value, wherein the encoder inverts a phase of one output signal among 2n(namely, N)-output signals in response to n-bit input value and outputs an encoded data value; and a decoder for decoding the output value of the encoder and restoring the original data value, wherein the decoder restores the original data value by adding an output value from the encoder and the previous original data value.