An apparatus for automatic color correction is provided, which includes an analog-to-digital converter (ADC), a plurality of section adders and a micro control unit (MCU). The section adders divide a test image signal through the ADC into sections and count the gray-level amount in each section. The MCU adjusts the offset and the gain of the ADC for automatic color correction, thereby ensuring that the color in the image signal almost appear to our eye as the true color.