WASHINGTON —A Federal Reserve Governor, Frederic Mishkin, will leave at the end of August and return to teaching at Columbia University, the central bank announced today. His departure means yet another empty seat on the Fed as it battles housing, credit, and financial debacles.

Mr. Mishkin, who has been on the Fed board since September 5, 2006, submitted his resignation to President Bush. His exit leaves the Fed with just four of its seven board seats filled.

“Rick’s contributions to the intellectual underpinnings of monetary policy at the Federal Reserve have been invaluable,” the Fed Chairman, Ben Bernanke, said. “His keen insights, deep analysis and humor have enriched our deliberations.”

Mr. Mishkin, 57, will return to Columbia University’s Graduate School of Business as a professor of economics and resume teaching in the fall, the Fed said.

The Fed’s meeting on August 5 will be Mr. Mishkin’s last.

An author of more than 15 books, Mr. Mishkin’s academic research has focused on how monetary policy affects financial markets and the economy at large.

“It has been a great privilege to serve my country in this capacity,” Mr. Mishkin wrote in his resignation letter to the president.

His departure comes as the Fed has been working urgently to help the economy recover from the blows of the housing slump, a painful credit crunch, and market turmoil.

The Fed, beginning last September, has carried out its most aggressive rate-cutting campaign in two decades to brace the wobbly economy. It also has taken a number of unconventional steps to help banks and investment houses overcome credit problems and help ease stresses in financial markets. One controversial move was the Fed’s financial role in backing JP Morgan’s takeover of investment house Bear Stearns, which teetered on the brink of bankruptcy in mid March.

Mr. Bush has nominated people — both bankers — to the two Fed board seats currently open, but the Senate hasn’t moved forward on confirmation proceedings. The Senate also hasn’t moved on Mr. Bush’s nomination of a Fed Govenor, Randall Kroszner, to a new term. Mr. Kroszner’s term has expired, although he is allowed to continue serving until a replacement is sworn in.

Mr. Bush selected Mr. Bernanke to be Fed chief and appointed all of the current members on the Fed’s board. That has allowed the president to put his imprint on the institution. The Fed sets interest rate policy and is responsible for the safety and soundness of the nation’s financial system.