B'Tselem, which monitors human rights in the occupied territories, said the figure included 141 children.
At least 322 had taken no part in hostile acts, the group said.
In the same period, the number of deadly Palestinian attacks on Israelis has fallen - 23 Israelis were killed in 2006 compared with 50 last year.
The Israeli military renewed ground operations in the Gaza Strip after militants captured an Israeli soldier in a border raid in June.
Since June, Israeli troops have killed about 405 Palestinians in Gaza, including 88 children. More than half of the casualties were civilians, B'Tselem said.
As of November, 9,075 Palestinians were being held in Israeli jails. This number included 345 minors, it said.
Of these, 738 (22 minors) were being detained without trial and without knowing the charges against them, the group said.