The National Labor Relations Board, a quasi-judicial federal agency both labor and management have fought to control since its establishment in 1935, is tilting more towards management under the Reagan administration.

That, at least, is the consensus of business and union leaders who have been watching the Reagan reconstruction of the NLRB. Two new Reagan appointees, Republicans John R. Van de Water and Robert P. Hunter, give the president's party a three-member majority. Both are serving as recess appointees pending Senate confirmation hearings. They are regarded as shoo-ins for Senate approval.

Hunter, former counsel and chief of staff to Sen. Orrin G. Hatch (R-Utah), chairman of the Senate Labor Relations Committee, is better known in Washington and more controversial than Van de Water. Hunter authored the section on restructuring the Department of Labor and the NLRB in "Mandate for Leadership: Policy Management in a Conservative Administration," published by the Washington-based Heritage Foundation, a conservative think-tank.

An excerpt from Hunter's essay on "NLRB deficiencies" reads: "Unfortunately, in many cases, the board has adopted an 'activist' stance, manifested by an anti-business, pro-labor bias . . . The perception of the board among the business community is that the board's enforcement and investigatory efforts are slanted against business."

Van de Water, an attorney and former management consultant from California, is respected for his advice to companies on how to keep unions out of their plants, according to management sources. He has also served as director of the executive training program at the University of California at Los Angeles graduate school of management, where he was a faculty member for 20 years.

Both Hunter and Van de Water declined requests for interviews pending their confirmation hearings.

Arthur Rosenfeld, an attorney for the U.S. Chamber of Commerce who is familiar with the NLRB's operation, welcomed the appointments. "The board's treatment of business has been horrible in the last four or five years," he said. "If you could put every labor and management lawyer in a room and ask them to give their candid opinions without fear of reprisal, they will tell you that the board has been everything organized labor could have possibly wanted . . . . "

Even with Van de Water and Hunter on board, "it's going to be a while before we can get the NLRB to at least swing to center," Rosenfeld said. "The problem is that the board has always been so politicized that every time there is a swing, it's a drastic swing from one side to another. But it looks like things are beginning to move in the right direction."

That view is disputed by Hugh J. Beins, a Washington attorney for the Eastern Conference of Teamsters who has practiced before the NLRB over the past 20 years. "It's a crazy thing to say that the board has been pro-union," Beins said. "At best, from our view, the NLRB has been moderate in its disposition of cases. No one can accuse it of vigorously enforcing the law," he said, referring to the 1935 National Labor Relations Act, more commonly known as the Wagner Act, that created the NLRB.

The Republican already on the board is Howard Jenkins Jr., regarded by labor as a moderate and by some in management as pro-union. He will complete 20 years of service when his fourth term expires in August, 1983. Three members is the maximum number any one party is permitted under the law.

Former board chairman John H. Fanning, bitterly opposed in many management circles, is a Democrat who will complete 25 years of service when his fifth term expires in December, 1982.

Don A. Zimmerman, a Carter-appointed independent who is also in disfavor with management groups, will finish his first term in December, 1984.

The Wagner Act that created the NLRB is the most significant labor law in the United States. The product of concern over business and labor turmoil wrought by the Depression, the act empowered the NLRB to:

Prevent and remedy employers' "unfair labor practices," which discouraged or interfered with the organization of unions.

Determine the bargaining unit at a plant or company in cases where two or more unions, or the employer, are disputing union representation rights.

Oversee union representation elections.

Beins and other labor lawyers contend that, in all but the last category, the NLRB has done poorly -- a charge career bureaucrats at the board deny.

"Things were so sad already that its a cruel joke to talk about what a 'liberal' or 'conservative' board might do," Beins said. But the Reagan administration's latest appointments, he said, means "things can only get worse."