Roy Eisenhardt, president of the Oakland A's, fired Manager Billy Martin yesterday and began searching for a successor. Eisenhardt said he had a long talk Tuesday with Martin before making the move.

"One must recognize the inevitability of change as a solution for difficult circumstances," Eisenhardt told Martin, "even when no party may seek or want this change."

Eisenhardt said Martin's contract, which runs through 1985 and calls for $250,000 a year, will be honored. He added Martin might return to the A's at a later date as an adviser, should he so desire.

Martin, who returned to his home in the San Francisco Bay area two years ago, has been fired by five American League teams. Martin, 54, was manager for Minnesota, Detroit, Texas, the New York Yankees (twice) and Oakland.

He helped the A's to the American League West title in the strike-shortened 1981 season. This year the A's drew more than 1.7 million fans, even though the club was not a contender and finished fifth in its division.

Former A's Manager John McNamara and former A's star Sal Bando were believed to be the front-runners for the Oakland job. McNamara managed the club for former owner Charles Finley and Bando played for him. Bando is currently an adviser to Harry Dalton, Milwaukee Brewers general manager. McNamara was fired as Cincinnati Reds manager last summer.

In a statement released late in the day, Eisenhardt said he was sorry his relationship with Martin did not work out.

"In no way does this action reflect adversely on you or the job you did," Eisenhardt said. "You are a valuable asset to baseball and we will always be among your greatest admirers. Hopefully, you may return to this organization in an advisory capacity when the time is ripe."

Martin was reportedly on a hunting trip and unavailable for comment. However, his agent, New Orleans judge Ed Sapir, released a statement from Martin.

Martin thanked Eisenhardt, Wally Haas, club vice president, and Walter Haas Jr., club owner, for "everything you have done for me. If there is a prince of people it is Mr. Haas."

Martin also was the general manager of the A's. Presumably, under new leadership, Eisenhardt and an adviser would handle most of the GM's duties, leaving the new manager to concern himself only with field duties.

A source close to Martin said he believed Martin would not take another job in baseball, "at least not right now. He would prefer to remain in the Bay area."

However, Gabe Paul, Cleveland Indians president, said Martin definitely is the top candidate to be the Indians' new manager. And Martin's agent has been in touch with the Yankees. Sources said the Yankees will actively pursue Martin.

Edward Bennett Williams, owner of the Baltimore Orioles, a team looking for a manager, expressed surprise about Martin's dismissal. When asked if Martin was a candidate for the Baltimore vacancy, Williams said: "He hadn't been . . ."

With Martin available, did that change? Williams wasn't saying.