A medium supply device includes a feeding unit that feeds a medium among one or more media placed on a placing table, a separating unit that is arranged to come into pressure-contact with the feeding unit, a blocking portion that is movable and blocks a space formed between the feeding unit and the separating unit in an upstream side of a nip region in a conveying direction of the medium, and a curve-forming portion that presses the medium against the feeding unit side to form a curve in a width direction of the medium.