A driving device and a source driving method are provided. The driving device includes a first code mapping unit, a first source driving channel, a second code mapping unit and a second source driving channel. The first code mapping unit converts a first input code in input data into a first intermediate code according to a first code-to-code mapping relation. The first source driving channel converts the first intermediate code into a first analog voltage according to a first code-to-voltage mapping relation. The second code mapping unit converts a second input code in the input data into a second intermediate code according to a second code-to-code mapping relation which is different from the first code-to-code mapping relation. The second source driving channel converts the second intermediate code into a second analog voltage according to a second code-to-voltage mapping relation which is different from the first code-to-voltage mapping relation.