Both have held their posts since President Bush took office in 2001 and are the first two Cabinet-level officials to announce their departure since the president's reelection.
Ashcroft said in a handwritten resignation letter dated Nov. 2 that "the demands of justice are both rewarding and depleting" and that the Department of Justice would be well served "by new leadership and fresh inspiration," Reuters reported.
Evans, a close friend of the president, said, "I have concluded with deep regret that it is time for me to return home."
"The president accepted their resignations," White House spokesman Scott McClellan said Tuesday evening.
Ashcroft drew criticism for many of the anti-terrorism measures implemented after the terrorist attacks of Sept. 11, 2001. Critics said the resulting USA Patriot Act infringed on civil liberties, but the Department of Justice Web site said the law had a hand in derailing over 150 terrorist plots and dismantling terrorist cells in six American cities.
Mr. Bush said in a statement that Ashcroft had "served our nation with honor, distinction and integrity" and had "transformed the [Justice] Department to make combating terrorism the top priority, including making sure our law enforcement officials have the tools they need to disrupt and prevent attacks."
Stress was a factor in health problems earlier this year that resulted in removal of the 62-year-old Ashcroft's gallbladder.
Speculation about a successor to Ashcroft has centered on his former deputy, Larry Thompson. If appointed, Thompson would be the nation's first black attorney general. Others prominently mentioned include Bush's 2004 campaign chairman, former Montana Gov. Marc Racicot, and White House general counsel Alberto Gonzales, according to the Associated Press.
A former oil and gas industry businessman, Evans ran the 40,000-worker Commerce Department tasked with promoting American businesses at home and abroad.
The president called him "a valuable member" of his economic team who worked to advance economic security and prosperity for all Americans.
Mercer Reynolds, national finance chairman for the Bush campaign who raised more than $260 million to get him reelected, has often been mentioned as a replacement for Evans.
Other Cabinet members who have said they are considering leaving are Secretary of State Colin Powell and Health and Human Services Secretary Tommy Thompson. Defense Secretary Donald Rumsfeld also has been mentioned as likely to leave.