To prevent generation of damage of a document by strong rubbing of a leading end and a rear end of the document at switch-back conveying without providing a mechanism for leaving a delivery roller.

In the image reading device, a first delivery roller 61a and a second delivery roller 61b are provided so as to clamp a document conveying route in a vertical direction, switch-back conveying is performed by the first delivery roller and the second delivery roller by switching a conveying direction of the document, and reading of both front and back surfaces of the document is enabled. The first delivery roller and the second delivery roller are arranged such that a conveying surface of the first delivery roller and a conveying surface of the second delivery roller are left from each other in a width direction relative to the conveying route of the document, and an inter-axis distance of the first delivery roller and the second delivery roller is made approximately equal to the sum of a radius Ra of the first delivery roller and a radius Rb of the second delivery roller.