A source driver includes: a first gradation voltage generation unit generating a gradation voltage of a first polarity supplied to a pixel on a first source line; a first amplifier receiving the gradation voltage of the first polarity to an input end, amplifying it, and outputting a voltage from an output end; a second gradation voltage generation unit generating a gradation voltage of a second polarity opposite to the first polarity to be supplied to a pixel on a second source line provided in the vicinity of the first source line; a second amplifier receiving the gradation voltage of the second polarity to an input end, amplifying it, and outputting a voltage from an output end; and a voltage comparison unit comparing a voltage of the input end of the second amplifier with the voltage of the output end of the second amplifier and outputs a comparison result.