It is his second foreign trip since being elected pope 13 months ago.
He was greeted at Rome's airport by Prime Minister Romano Prodi and other senior government figures and religious dignitaries, after arriving there by helicopter, where he boarded an Alitalia flight to Poland.
During the visit he will travel to the birthplace of Karol Wojtyla, and to all his favourite holy places, including the Jasna Gora monastery, where Poland's Black Madonna icon resides.
Like John Paul II, he will also visit the Auschwitz-Birkenau Nazi concentration camp, where he is expected to pray for reconciliation between nations and faiths.
The German-born pontiff will also celebrate a public mass in Warsaw.
The Polish authorities have gone to great lengths to ensure the pope's security, mobilising 15,000 police officers and calling on NATO to deploy a plane to monitor Polish air space during the visit.
The Pope -- who already speaks fluent French, English, Italian, Spanish and Latin -- is said to have taken intensive lessons in Polish.