Yossi Sariel will be leaving his role shortly, according to the military.
The prestigious and secret unit 8200, which he is in charge of, is responsible for decoding and analyzing various intelligence.
Israeli media report that Sariel, in his farewell letter, apologizes for not having succeeded in "fulfilling the mission entrusted to us".
Earlier, it was reported that the unit had intelligence documents warning of Hamas' preparations for the attack. The document contained details, among other things, about Hamas fighters training to take hostages.
More than 1,100 people were killed in Hamas' attack on October 7, 2023, and around 250 people were taken hostage.
Since Israel declared war on Hamas after the terrorist attack, more than 41,000 people in Gaza have been killed in Israeli attacks, according to health authorities in the Hamas-controlled strip.
