Image reading apparatus, control method of image reading apparatus, and storage medium

An image reading apparatus comprising:

• a feeding unit configured to feed a document;
• a reading unit configured to read a first side of the document fed by the feeding unit and an image on a second side of the document by reversing the document;
• a storing unit configured to store image data of the document read by the reading unit;
• a determining unit configured to determine whether a free capacity of the storing unit is equal to or greater than a predetermined size;
• and
• a control unit configured to control the reading unit so that, for a first document and a second document fed by the feeding unit, an image on a second side of the first document is read after a first side of the first document fed by the feeding unit is read and a first side of the second document following the first document is read in a case where the determining unit determines that the free capacity of the storing unit is equal to or greater than the predetermined size, and configured to control the reading unit so that the first side of the second document following the first document is read after the first side of the first document fed by the feeding unit is read and the image on the second side of the first document is read in a case where the determining unit determines that the free capacity of the storing unit is not equal to or greater than the predetermined size.