A driving circuit of a display device including a TFT (Thin Film Transistor) liquid crystal display device or the like is provided which is capable of decreasing a chip in size and reducing costs of testing by reducing the number of bits even in the case of increased number of bits of digital image data to perform multi-gray shade displaying. The driving circuit of the display device has a gray shade voltage generating circuit adapted to generate a plurality of voltages, gray shade voltage selecting circuits used to select one voltage out of a plurality of voltages supplied from the gray shade voltage generating circuit based on high order bits composed of one or two and more bits counted from the most significant bit of the digital image data and the number of bits of which is smaller than that of the digital image data and to output it, operational amplifiers used to convert an impedance of a voltage outputted from gray shade voltage selecting circuits and voltage adjusting circuits used to induce a voltage rise or a voltage drop in voltages outputted from the operational amplifier based on low order bit of the digital image data excluding its high order bits.