PURPOSE: To reduce reading error by providing two two-dimensional image sensors shifted slightly with a position where an image is formed and selecting an image sensor output larger in amplitude among the two-dimensional image sensors.

CONSTITUTION: When a hand scanner scans an original at a normal position 3-1, a complete image is formed on the two-dimensional image sensor 1-1 and a defocused image is formed on the two-dimensional image sensor 1-2. On the other hand, when the hand scanner is parted from an original and an apparent position goes away as shown in the position 3-2, the image of the original 3 is formed to the sensor 1-2 and the image of the 1-1 is defocused. It can be said that the formed image larger in difference between white and black levels is complete among electric outputs of both the sensors 1-1 and 1-2. Thus, a signal having good accuracy and without blur is obtained by comparing the output waveform of the sensors 1-1 and 1-2, and selecting the signal larger in difference between the maximum value and the minimum value.