PURPOSE: To provide a lower nozzle to a fuel assembly for a pressurized water nuclear reactor, which efficiently traps foreign matter in coolant passing therethrough so as to prevent the foreign matter from causing fretting damage to a fuel rod, and which can hold and collect thus trapped foreign matter.

CONSTITUTION: A plurality of horizontal partition plates 3a, 3b, 3c are laid below the top support plate of a lower nozzle body 1 in which vertical water flow holes 1c are perforated, so as to define trap space layers 2a, 2b, 2c having heights 11, 12, 13 therebetween which are downwardly larger and larger in that order. Several trapping vertical water flow holes 4a, 4b, 4c are formed in the horizontal partition plates 4a, 4b, 4c, those of the holes which are vertically adjacent to the vertical water flow holes 1c being laterally shifted so as to make the trap space layers 2a, 2c, 2b have a trapping function over their entire areas so that they can traps foreign matter having large to small sizes, respectively, and they can hold and remove the foreign matter without dropping the same.