An apparatus for automatically loading a fuel pellet for manufacturing a nuclear fuel rod is provided. The apparatus includes a tray transfer unit that horizontally transfers the tray, a fuel pellet alignment unit that aligns fuel pellets arranged in the tray, a measurement unit that measures an entire length of the fuel pellets arranged in a row on the tray, a controller that compares an accumulated measured length with a set length, a waiting table located adjacent to the tray transfer unit to store a redundancy fuel pellet, and a fuel pellet movement unit that is driven by the controller and moves the fuel pellets between the tray and the waiting table.