Almost 53% said Israel was not serious about the withdrawal, slated for completion by end-2005, according to the poll published on Monday.
The poll was carried out by Birzeit University this month. It has a 3% margin of error.
Only 19.6% thought the pullout would take place as planned, while 25.2% said the Jewish state was serious "to some extent".
The remainder did not have an opinion.
While 50% predicted the withdrawal would be partial, 11.3% said it would be implemented in full and 38.4% believed it would not take place.
A majority said Yasir Arafat's Palestinian Authority was qualified to take over the administration of Gaza, while 24.7% thought not and 30.7% said it was capable "to some extent."
A slim majority of respondents said they believed the PA could improve living conditions in the impoverished territory, which is home to 1.3 million Palestinians, most of them unemployed.
Survey said Arafat's PA capable
of administering Gaza
Some 28.9% said the PA would not and 33.2 said it might in a limited fashion.
A towering 76.6% estimated the withdrawal would reinforce Israel's occupation of the West Bank, where only four settlements will be dismantled as part of the same evacuation plan. Only 14.6% deemed it would not.
The remaining 5.3% were undecided.
In contrast, 46.6% said the pullout would lead to additional security for Palestinians in Gaza, while 29.7% said it would moderately improve security and 20.5 said it would not.
Earlier in June, the Israeli government backed Sharon's plan to end the Jewish presence in the Gaza Strip and part of the West Bank.
The move affects about 7,500 Gaza settlers, but only around 400 in the West Bank, which is home to 220,000 Jewish settlers.
The poll also showed that most Palestinians would prefer general elections to be conducted immediately after the evacuation and saw a unified leadership, not Arafat's ruling Fatah party, as most apt to rule Gaza.