Image reading apparatus

An image reading apparatus, comprising:

• an apparatus body including an insertion port into which a sheet medium is insertable;
• an existing light source that is provided in the apparatus body and illuminates when an image is read with respect to the sheet medium that has been inserted into the insertion port;
• a light guide and output unit that is optically connected to the existing light source, guides light emitted from the existing light source, and outputs the guided light into the insertion port;
• a light receiving unit that detects the output light;
• and
• a determining unit that determines whether the sheet medium has been inserted into the insertion port based on a result of the detection by the light receiving unit,
• wherein
• the existing light source also illuminates when the determining unit determines whether the sheet medium has been inserted into the insertion port, and
• a region in the insertion port through which the light output from the light guide and output unit passes exists from one end to the other end of the insertion port in a width direction that is a longitudinal direction of the insertion port.