A paper feeder capable of reducing its installation space and manufacturing cost, wherein a paper feed table which can be lifted or lowered being held horizontal is provided with an opening section. In order to load paper sheets onto the paper feed table directly from above, the opening section is made openable upwards when the paper feeder is in a paper feeding state during which paper sheets are picked up and fed to a photosensitive drum or similar device. The paper feeder also has a pick-up member for picking up the paper sheets thus loaded onto the paper feed table one after another starting with the top sheet in order to feed them to the photosensitive drum or similar device.