An image read apparatus includes a group of CCDs reading out a document image, a data processing unit, a line buffer to delay data to obtain data of the same pixel, a comparison unit comparing data of the same pixel, a data table in which a threshold value that becomes the reference of comparison is stored in correspondence with each type of mode, a threshold value set unit referring to the data table to set the threshold value, a determination unit receiving the comparison result with the threshold value from the comparison unit to determine and control data to be sent downstream, and an averaging unit averaging the data sent from the determination unit to output the average as image data. An image read apparatus is provided that can prevent generation of a black streak or a white streak on a readout image caused by the presence of dust at the readout position, and that can improve the picture quality of the entire image.