A medium conveying apparatus includes a housing including an accommodation portion provided with a guide portion at an end portion in a width direction, a tray accommodated in the accommodation portion so as to be pulled out, and including a placing surface for placing an ejected medium, and an engaging portion provided on a side surface of the tray, to engage the guide portion. The guide portion includes a pair of rails inclined upward and having a predetermined width. The engaging portion includes two protrusions provided so as to slide between the pair of rails and located apart from each other by a predetermined distance. By locating the two protrusions between the pair of rails, the tray is positioned at a predetermined position with respect to the housing with a front end portion of a downstream side in the medium ejecting direction located upward.