Abstract: A color sensor has a layered body obtained by stacking a first photoelectric sensor which is constituted by an amorphous semiconductor having a "PIN" structure and a spectral sensitivity which has a peak with respect to blue light and a second photoelectric sensor which is constituted by an amorphous semiconductor having a "PIN" structure and a spectral sensitivity which has a peak with respect to red light, so that a p-n junction is formed therebetween, and a pair of electrodes with each of the electrodes being provided at a respective end of the body, at least one of the pair of electrodes being transparent. A color measuring apparatus uses the color sensor with a bias voltage supply for supplying three different bias voltages between the sensor and the pair of electrodes, a photo-current detector for detecting photo-currents for each bias voltage and a color discriminator for discriminating incident light color on the basis of the detected photo-currents.