A paper feeder includes a sheet supply unit that feeds sheets placed on a sheet placing part, a separating roller the separates the sheets fed by the sheet supply unit one sheet at a time and supplies each sheet to a sheet transportation path, a transportation roller that transports the sheets provided downstream of the separating roller and a link mechanism connected to the transportation roller via a transmitting unit. When the transportation roller rotates in a sheet transporting direction, the link mechanism swings so that a shutter opens the sheet transportation path and maintains an opened state. When the transportation roller rotates in a direction opposite to the sheet transporting direction, the link mechanism swings so that the shutter closes the sheet transportation path.