Airport spokeswoman Karin Heldeweg said Schiphol's Pier C was shut down for arriving and departing flights while bomb disposal experts checked the suspected explosive and decided what to do with it.
The airport warned passengers that the pier's closure could lead to delays and cancellations. Around noon (1000 GMT), Schiphol's website showed many flights to and from the airport delayed and departures to destinations including Glasgow, Scotland, Gothenburg, Sweden, and Frankfurt, Germany, cancelled.
The suspected bomb was uncovered early Wednesday by workers digging trenches near the pier to lay pipes. The pier houses many of Schiphol's departure and arrival gates.
Nazi forces who occupied the Netherlands in WWII took over Schiphol and used it as a base for Luftwaffe aircraft. It was repeatedly bombed by Allied air forces.
The scare at Schiphol came a day after a World War II bomb was detonated in the German city of Munich, sparking fires in several nearby buildings that had been evacuated after the bomb was discovered Monday.