A paper feeder includes a storage section, a feed path, a delivery section, and a receiving section. The storage section is configured to store therein plural sheet members to be fed to a processing apparatus which is operative to perform processing on the sheet members. The feed path allows each of the plural sheet members fed from the storage section to pass therethrough in a feed direction toward the processing apparatus. The delivery section is located most downstream on the feed path in the feed direction. The feed path is open to exterior in the delivery section. The receiving section is located upstream of the feed path in the feed direction for communication with a delivery section of a separate paper feeder having an identical construction with the present paper feeder when the separate paper feeder is disposed upstream of the present paper feeder in the feed direction.