FIG. 2A is a diagram illustrating an example of how the sheet P is placed on the platen glass 30 in first sheet reading (first state). FIG. 2B is a diagram illustrating an example of how the sheet P is placed on the platen glass 30 in second sheet reading (second state). A letter F on the sheet P in FIGS. 2A and 2B is drawn to facilitate understanding of the orientation of the sheet P, but is not essential. Here, the letter F may be printed on the sheet P so that an operator or the like can understand the orientation of the sheet P, or another letter, symbol, pattern, or the like may be printed on a predetermined portion of the sheet P. As illustrated in FIG. 2A, in the first time, the sheet P is read in a state (a first state) in which an upper side 76 of the sheet is directed to a first side Dir1 in a main scanning direction DH (direction perpendicular to the sub-scanning direction DM). As illustrated in FIG. 2B, in the second time, the sheet P is read in a state in which the upper side 76 of the sheet is directed to a second side Dir2 in the main scanning direction DH. The state in the second time may be referred to as a second state and is the same as a state in which the sheet P is directed to a side opposite to a side in the first state and a state in which the sheet P in the first time is rotated by 180 degrees. In both the first and second times, the sheet P is placed on the platen glass 30 so that the recess of the crease 70 faces down. Further, in both the first and second times, the sheet P is placed on the platen glass 30 so that the crease 70 is in a direction intersecting the sub-scanning direction DM (the moving direction of the illumination unit 20).