A paper feeder of a printer has a plurality of paper feeding paths to feed a printing paper, and a main fed roller feeding the printing paper to an image forming unit of an image forming apparatus. The paper feeding paths are disposed along an outer circumference of the main fed roller and confluent along a connecting conveyance path by the main feed roller. The connecting conveyance path is connected with a main conveyance path which guides the printing paper to the image forming unit of the image forming apparatus. By a single feed roller, the printing paper from the paper feeding cassette in an automatic paper feeding mode, the printing paper from a manual paper feeding tray in a manual paper feeding mode, and the printing paper being inverted and returned in double-sided printing, can be fed to the paper conveyance path efficiently. Because there is no need to prepare a separate feeding apparatus to convey the printing paper according to the respective printing modes, a structure of the printer can be simplified, and an internal space of the printer is reduced. As a result, a compact-sized printer requiring less manufacturing costs can be provided.