Image reading device and auto document feeder

An image reading device comprising:

• a reading portion at which one side of a document is read;
• a document type specifying device configured to specify whether the document is a first type document or a second type document of which length in a feed direction is longer than the first type document;
• and
• a feed controller configured or programmed to perform a U-turn control and a switchback control, the U-turn control being a control in which after a first side of the first type document has been read at the reading portion, the first type document is fed in a U-turn manner without switching back, and a second side of the first type document is read at the reading portion, and the switchback control being a control in which after a first side of the second type document has been read at the reading portion, the second type document is caused to switch back, and a second side of the second type document is read at the reading portion;
• wherein
• in the switchback control, the feed controller is configured or programmed to cause the second type document to switch back and to pass the reading portion in a second direction after causing the second type document to enter the reading portion in the first direction and reading the first side, and then to cause the second type document to switch back again such that the second type document enters the reading, portion in the second direction, the second direction being opposite to the first direction.