An image scanning apparatus comprising a plurality of image scanning sensors 21, 31, 41, and a CIS control chip 50 for controlling these image scanning sensors 21, 31, 41. The CIS control chip 50 has a trigger generator 54 for controlling operation of the image scanning sensors 21, 31, 41, a lamp control circuit 55, and a motor control circuit 56. The CIS control chip 50 also has an AFE 51 having a plurality of input terminals 51a to 51c for receiving the analog image signals from the first scanning sensor 21, second scanning sensor 31, and third scanning sensor 41, respectively and a gain/offset control circuit for adjusting the gain and offset of each line of analog data supplied from the image scanning sensors 21, 31, 41.