Iraqi Finance Minister Rafa al-Essawi announced his resignation on Friday at an anti-government protest in Ramadi, west of Baghdad, an AFP journalist said.
"I am with you, I am your son, and I announce today... that I am presenting my resignation from the Iraqi government, and I will not return to this government," Essawi, a leading Sunni, told thousands of demonstrators.
Protests have been staged in Sunni-majority areas of Iraq in recent weeks, calling for the resignation of Prime Minister Nuri al-Maliki and decrying the alleged targeting of their community by the Shiite-led authorities.
The protests were initially sparked in December by the arrest of several of Essawi's guards.
But they have since expanded markedly, and the government has sought to curtail them by claiming to have released thousands of detainees and raising the salaries of Sunni militiamen fighting Al-Qaeda extremists.