A medium discharge device includes a discharge roller pair that is provided with a discharge driving roller and a discharge driven roller which drivably rotates in contact with the discharge driving roller, and a medium receiving tray which receives the medium that is fed and discharged by the discharge roller pair, in which the medium receiving tray includes a guide member which guides such that a tip end of the medium which is discharged from the discharge roller pair enters the medium mounting surface at a predetermined angle, and the guide member is provided to be elastically displaceable in an advancing and retreating direction with respect to the medium mounting surface of the medium receiving tray and is displaced in a direction coming close to the medium mounting surface according to raising of a pressing load due to the medium that is discharged to the medium receiving tray.