A medium discharging device for receiving a medium discharged from a discharge portion of a processing device, the device comprising: a placement portion that is disposed below a height position of the discharge portion in a vertical direction and has a placement surface on which the discharged medium is placed; and a guide member that is provided to be advanced and retracted between an advanced position where the guide member is advanced inward in a width direction intersecting a discharge direction of the medium from opposite sides in the width direction and a retracted position where the guide member is retracted to an end portion position side in the width direction, wherein when the guide member is disposed at the advanced position, an upstream side end portion of the guide member in the discharge direction is disposed in a height position between a height position of a discharge position by the discharge portion in the vertical direction and a height position of the placement surface of the placement portion in the vertical direction, and wherein in the guide member, with one end side on a downstream side in the discharge direction as, at or near a pivotal shaft, the other end side, which corresponds to the upstream side end portion, is advanced and retracted between the advanced position and the retracted position, characterised in that a height position of the other end side of the guide member in the vertical direction when the guide member is disposed at the advanced position is lower than a height position of the other end side of the guide member in the vertical direction when the guide member is disposed at the retracted position. a placement portion that is disposed below a height position of the discharge portion in a vertical direction and has a placement surface on which the discharged medium is placed; and a guide member that is provided to be advanced and retracted between an advanced position where the guide member is advanced inward in a width direction intersecting a discharge direction of the medium from opposite sides in the width direction and a retracted position where the guide member is retracted to an end portion position side in the width direction, wherein when the guide member is disposed at the advanced position, an upstream side end portion of the guide member in the discharge direction is disposed in a height position between a height position of a discharge position by the discharge portion in the vertical direction and a height position of the placement surface of the placement portion in the vertical direction, and wherein in the guide member, with one end side on a downstream side in the discharge direction as, at or near a pivotal shaft, the other end side, which corresponds to the upstream side end portion, is advanced and retracted between the advanced position and the retracted position, characterised in that a height position of the other end side of the guide member in the vertical direction when the guide member is disposed at the advanced position is lower than a height position of the other end side of the guide member in the vertical direction when the guide member is disposed at the retracted position.