The present invention relates to a liquid crystal display device with a source driver in which a significant signal delay is not generated, and which has a fast response speed. The present invention also provides a liquid crystal display device comprising a scan driver including a D/A converter for outputting analog signals corresponding to gradation data input, a triangular wave generator for outputting triangular wave signals, and a comparator for applying data voltage to each pixel which include OCB liquid crystal cells by comparing the analog signals with the triangular wave signals. The data voltage is a PWM pulse with a varied voltage width.