PURPOSE: To eliminate read error caused by the nonuniformity of sub scanning carrier or the oscillation of an image to be read by performing sub scanning while moving a main scanning means in the state of holding a transmitting original.

CONSTITUTION: Concerning a scanning means 14, a driving source 32 is held on a stage 30 movable in a sub scanning direction (y) and a main scanner 36 for deflecting read light L in a main scanning direction (x) is arranged at the head part of a rotary shaft 34 of the driving source 32. The driving source 32 is driven, a mirror 38 of a main scanning part 36 is rotated in the main scanning direction (x,) the read light L is emitted from a light source unit 12, the stage 30 starts moving in the sub scanning direction (y) and reading is started. The read light L reflected by the mirror 38 is made incident to strips A held at a prescribed position by a holding means 16, and the strips A are two-dimensionally scanned. The read light carrying image information after transmission through the strips A is made incident to an integration ball 18, scattered in the integration ball 18 and made incident to photoelectric conversion elements 20R, 20G and 20B.