A report on the Guard's website said Gen. Ghodratollah Mansouri accidentally shot himself in the head while cleaning his pistol.
The report said Mansouri was veteran of the 1980s Iran-Iraq war and a "defender of the shrine," a reference to Iranians who fight the Daesh terror group in Syria and Iraq.
Since 2014, Mansouri was a regional commander of the Guard's ground forces in the northeastern city of Mashhad, some 900 kilometers east of the capital Tehran.
Hundreds of Iranian forces have been killed fighting Daesh in Syria and Iraq.
Iran, the regional key supporter of Syria's government, says its forces there only perform an advisory role.
