Fairfax County Supervisor James M. Scott (D-Providence), one of the last remaining members of a liberal coalition that dominated the county board in the early 1970s, has decided to resign effective June 3.

Scott, who said he has accepted a position in community relations for a nonprofit organization in Fairfax, said he plans to announce his decision at the Fairfax County Board of Supervisors meeting today.

Scott, a 47-year-old consultant, has taught government at Northern Virginia Community College. However, he declined to identify the organization he will work for.

"This opportunity was a very good one," Scott said last night in explaining his decision. "I never really thought of myself as having a career on the Board of Supervisors, and when this opportunity came along it was important for me to think about how long I was going to do this, as much as I enjoyed it.

"I really feel . . . it's really time for something new for me as well as someone new for the board," he said. He added, "The enjoyment is not as great as it used to be.

"Basically, yes," he said, "I'm retiring from politics."

A tall, soft-spoken man, Scott has represented the Providence district since 1972. His resignation from the nine-member board could further jeopardize the position of Fairfax Democrats, who lost control of the board two years ago for the first time in a century. Republicans hold a 5-to-4 majority on the board.

Scott's term does not expire until the end of 1987. Under state law, a special election to choose Scott's successor would be held no sooner than 30 days after he resigns. In the intervening period, his 86,000 constituents would be left without a representative on the board.

Scott's district, an elongated, irregular product of artful boundary-drawing, stretches from Seven Corners near the Arlington County line in the east to Stringfellow Road in the far west.

It includes Tysons Corner as well as the Fair Oaks Mall west of Fairfax City, two of the fastest-growing spots in the area.

Board Democrats said an election to fill Scott's seat will be critical.

"I don't think we could afford to lose another seat on the board," said Supervisor Joe Alexander (D-Lee), the senior Democrat on the board. "If we lost, it would be difficult to regain a majority in '87."

Sources said the most likely Democratic candidates to replace Scott are Katherine Hanley, the School Board member from the Providence district; Kevin Bell, president of the County Council of PTAs, and Rosemarie Annunziata, a Planning Commission member from the district.

Although there had been no indications that Scott was planning to resign, he has been under political pressure in recent months from board Republicans, who have threatened to redraw the boundaries of the county's eight magisterial districts.

Democrats said that any such redistricting would be aimed primarily at ousting Scott, who has never won an election for county supervisor with more than 53 percent of the vote, and at increasing Republican domination of the board.

Even without redistricting, politicians said, Scott seemed likely to face a tough and well-financed challenge in the 1987 elections.

Although politicians in Fairfax often spoke of Scott's vulnerability, he is one of Northern Virginia's most durable Democratic elected officials, winning four straight elections in the Providence district despite -- or because of -- periodic redrawing of political boundaries.

Running for his fourth four-year term in 1983, he was opposed by a Republican as well as an independent, both of whom were spurned by Scott when they sought political appointments earlier.

The board's leading advocate of public housing, Scott occasionally has raised the hackles of Republicans, who have called him out of step with the conservative times. On some social issues, such as divesting the county of its South Africa-related pension holdings, Scott has been a lonely voice on the board.