Image reading device and method for determining accompaniment by metal object

An image reading device that transports a document stacked on a document stacking table to a document transport path and reads an image formed on the document, the device comprising:

• a magnetizer that magnetizes a metal object attached to the document;
• a magnetism detector that is disposed on a downstream side of the magnetizer in a document transport direction from the document stacking table toward the document transport path and detects residual magnetism of the metal object;
• and
• a metal object accompaniment determination unit that determines whether or not the metal object is attached to the document based on a detection result of the magnetism detector.