The invention provides an automatic document conveyance device and an image reading apparatus using the same. The automatic document conveyance device, include a paper guide which has a slot formed by cutting off a part of a conveyance surface for guiding a document; a conveyance unit which inserts in and detach from the slot; wherein the conveyance unit further comprising: a motor which generates driving force; a motor holding part which holds the motor; a driving roller which conveys a document; a drive transmission mechanism which transmits the driving force generated by the motor to the driving roller via a driving roller shaft; and a fitting part which fits the conveyance unit into the slot so that one surface of the conveyance unit forms the conveyance face.