PURPOSE: To easily reproduce a read position and an angle by setting an original once more even when the original is once removed from the reader.

CONSTITUTION: The image input device is provided with a lighting means lighting an original, a photoelectric conversion means reading the image of the lighted original, an original support means 60 supporting the original, and a placing means 47 on which the original support means 60 is mounted. Then the original support means 60 has a positioning hole 67 (or positioning shaft), a 1st side wall, the placing means 47 has an engagement shaft 100 (or engagement hole) engaging with the positioning hole 67, and energizing means 97, 98 in press contact with the 1st side wall and energizing the original support means 60 in a direction of the engagement position between the positioning hole 67 (or positioning shaft) and the engagement shaft 100 (or engagement hole). The original is positioned by the engagement between the positioning hole 67 (or positioning shaft) and the engagement shaft 100 (or engagement hole) and the energizing of the energizing means 97, 98 to the 1st side wall.