Disclosed is a fuel rod testing apparatus for a nuclear fuel assembly. The fuel rod testing apparatus includes a helium leakage testing chamber having a gate so that a fuel rod is horizontally loaded/unloaded and testing whether or not helium leaks from the fuel rod, a fuel rod upward/downward transfer unit that has first and second transfer sections located in front of the gate and horizontally installed apart from each other in order to guide the fuel rod loaded into or unloaded from the helium leakage testing chamber, and that vertically drives the first and second transfer sections, and a main frame that has a upper transfer section disposed in parallel in a lengthwise direction of the fuel rod upward/downward transfer unit and having an inclined face and a lower transfer section installed at a lower portion of the upper transfer section and having an inclined face.