The Senate yesterday, in a major victory for President Reagan, voted 57 to 42 to confirm Kenneth L. Adelman as the new director of the Arms Control and Disarmament Agency.

The vote culminated a three-month debate in the Senate not just over Adelman but over administration commitment to arms control generally.

In his news conference at the White House, Reagan said he was "deeply gratified" by the Senate action and added, "It is my earnest hope that this will mark the beginning of a new bipartisan consensus on the vital issue of nuclear arms reductions."

Reagan also held out the hope that "if we're met with reciprocal seriousness of purpose from the Soviet Union, 1983 can be a year of historic importance in securing a solid and stable peace through arms reductions."

The president also said that ACDA, under Adelman's leadership, would be "reinvigorated." The arms control agency is supposed to be a focal point for the formulation of arms control policy in the executive branch. In practice, in this and other administrations, the main decisions have been made at higher levels.

Sen. Charles H. Percy (R-Ill.), chairman of the Senate Foreign Relations Committee and leader of the fight to have Adelman confirmed, said before the vote that because of commitments made by the White House during the long debate, "Adelman has leverage" within the administration to press for arms control and reduction agreements "and his supporters do, too."

In New York, where he has been deputy U.S. representative to the United Nations, Adelman said he was "extremely pleased" and announced that he would seek individual meetings next week with every member of Foreign Relations, whose members had voted 9 to 8 against his confirmation. "Such close consultation," he said, "can help our arms control efforts, which, in my view, must be bipartisan to be effective."

Adelman was nominated in January to succeed Eugene V. Rostow, who was fired. Opponents said Adelman lacked the experience and commitment to arms control the job requires, and two Democrats on the committee who had led the fight against Adelman voiced their continued disappointment yesterday.

Sen. Paul E. Tsongas (D-Mass.), who had complained that Adelman views arms control as a sham, told reporters "the Russians are going to make hay with this in Europe."

Sen. Alan Cranston (D-Calif.), a presidential candidate who has adopted arms control as a major campaign theme, declared the Senate vote was "a victory for the enemies of arms control within the Reagan administration."

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) declared that having spent time with Adelman over the past weeks, he was "sure he has the will and capacity to become an outstanding advocate of arms control."

The vote was larger than expected for the nominee as a few Democrats and several liberal Republicans, who had been listed as opposed, threw their support to Adelman at the last minute in response to presidential persuasion. Forty-nine Republicans and eight Democrats supported Adelman; 38 Democrats and four Republicans--Charles McC. Mathias Jr. of Maryland, Larry Pressler of South Dakota, Mark Andrews of North Dakota and Slade Gorton of Washington--voted against him.

"We brought out the big guns," was the way one Reagan aide described the efforts made over the past few days by the president, Vice President Bush, Secretary of State George P. Shultz and others in behalf of the nomination, loss of which would have been a serious blow to the president's prestige.

Sen. Arlen Specter (R-Pa.), announced he would back Adleman shortly before the vote. He said he had spoken with the nominee less than an hour earlier and had received a "commitment that he would be the advocate for arms control and arms reductions." Specter told his colleagues he had also had a 10-minute telephone conversation with the president on behalf of the nominee as well as visits from William C. Clark, the president's national security affairs adviser, and the two U.S. arms control negotiators, Paul H. Nitze and Edward L. Rowny.

Another liberal Republican, Sen. Lowell P. Weicker Jr. of Connecticut, said he voted for Adelman because he "wanted the administration to have no excuse" for not coming up with an arms agreement.