An image reading apparatus that optically reads a document includes: multiple line sensors provided approximately parallel to each other and each having light-receiving elements arranged in line form, each line sensor capturing respective line-shaped regions spanning in the main scanning direction of the document in respective color components; a movement unit that causes the positional relationship between the document and the multiple line sensors to move relative to the sub scanning direction that is orthogonal to the main scanning direction; a color skew adjustment unit that adjusts positional skew in the sub scanning direction in scan data of each of the color components captured by the multiple line sensors in synchronization with the movement caused by the movement unit, in accordance with an offset amount based on the distance between each of the multiple line sensors.