PURPOSE: To read in a video signal with good accuracy against the variance of a video signal level, by providing a means to change the discriminatin level of read- in video signal from the next line, depending on the video signal of read- in line whether it is all white or not.

CONSTITUTION: When lines L1∼L4 of a transmission original 1 are read in with a CCD image sensor 6, analog video signals AP1∼AP4 are outputted from an amplifier 7. Two types of discrimination level signals S, S' are applied to a discrimination circuit 8 from a switching circuit 10, and the circuit 8 performs the identification of a white pattern signal W and a black pattern signal B with a discrimination level signal S to the analog signals AP2 and AP4 and does the same with the signal S' to the analog video signal AP3. As a result, the circuit 8 outputs a video signal DP3 when the analog signal AP3 is lower than the signal S' at blocks D, E and F.