A semiconductor device includes a plurality of synchronization clock generators configured to generate a plurality of synchronization clock signals by mixing phases of first and second source clock signals having an identical frequency, a first clock transmission path configured to sequentially apply the first source clock signal to the plurality of synchronization clock generators by transferring the first source clock signal in a forward direction, a second clock transmission path configured to sequentially apply the second source clock signal to the plurality of synchronization clock generators by transferring the second source clock signal in a backward direction, and a plurality of data output units configured to synchronize a plurality of data with the plurality of synchronization clock signals and outputting the synchronized plurality of data.