Disclosed are a source driver capable of achieving high speed and high resolution and a display driving circuit including the same. The source driver may include: a first channel group and a second channel group configured to output source driving signals; a first gradation voltage divider configured to generate first gradation voltages using gamma reference voltages and provide the first gradation voltages to the first channel group; and a second gradation voltage divider configured to generate second gradation voltages having the same level as the first gradation voltages using the gamma reference voltages, and provide the second gradation voltages to the second channel group. The first and second gradation voltage dividers are connected to a gamma reference voltage generator configured to provide the gamma reference voltages, and receive the gamma reference voltages having the same voltage range from the gamma reference voltage generator.