A special electoral college today overwhelmingly elected opposition leader Tancredo de Alimeda Neves as Brazil's first civilian president after 21 years of military rule.

Neves, 74, received 480 votes in the 686-member college, made up of the elected Congress and delegates from state legislatures. A centrist leader of the Brazilian Democratic Movement, he was supported by an alliance of opposition parties and dozens of defectors from the military-backed government party.

In a speech following the vote in the central chamber of the Congress, Neves described his victory as the product of a national consensus and promised a reformist government.

"I come in the name of conciliation," he said. "I came to promote change -- political change, economic change, social change . . . real, effective, courageous, irreversible change."

Paulo Maluf, 53, the candidate of the official Social Democratic Party, received 180 votes, despite his party's majority in the college.

"I am happy to be here," he told the assembly in a speech before the voting began, "because my candidacy guaranteed the political process."

Brazil's 130 million people had no direct participation in the election. The outgoing military, which permitted open congressional elections in 1982, refused to allow a popular vote for president.

Neves' candidacy, however, appeared to have strong public support. Noisy street celebrations began early this morning and continued throughout the day in cities and towns across the country as citizens gathered to watch television broadcasts of the election.

The vote took little time. Packing the aisles of a circular congressional chamber with journalists watching from the gallery, the electoral delegates began shouting out their votes by roll call shortly before 10 a.m. Ninety minutes later, as Neves received the decisive vote, the delegates stopped to cheer and embrace each other and fireworks and a cacophony of honking horns erupted on the streets outside.

Leaders of the armed forces, who designed the electoral college system as a way of preserving control over Brazil's federal government for another six years, said they would accept the opposition victory and end their rule when Neves is inaugurated March 15.

The new government has promised not to investigate corruption or human rights abuses of the long military administration. Armed forces leaders are expected to retain substantial influence over areas of the nation's administration, ranging from arms manufacturing to communications.

Neves, a congressman and a prime minister in the last democratic government before the military's 1964 coup, formally was elected to a six-year term and will retain the special powers held by outgoing President Joao Figueiredo, a retired general.

Neves promised today to support a constituent assembly to reform the constitution. and he is expected to call direct popular elections for a successor in 1988.

"I call you to a great constitutional debate," he said. "We acted within the imposed rules exactly in order to revoke them and destroy them."

Neves' election, assured months before the actual vote, was viewed by politicians of all ideologies as a compromise to return Brazil to full democracy. Figueiredo, who has led the military's slow process of abertura, or opening to democracy, since 1979, originally planned to "coordinate" the choice of his successor with military backing.

However, as a severe economic crisis and the military's political exhaustion weakened the government, Figueiredo was unable to control dissidence among the civilian politicians of the Social Democratic Party. Maluf, a conservative who is independent of both the military and Brazil's traditional political establishment, won the presidential nomination without the president's support.

Opposition parties mobilized millions of people in a nationwide campaign for direct elections last year, but the initiative, strongly opposed by Figueiredo and the military, was voted down by the Social Democratic Party in Congress.

Then, after weeks of intense negotiations, dozens of Social Democrats, led by Aureliano Chaves, Figueiredo's civilian vice president, agreed to back Neves over Maluf in the electoral college. Jose Sarney, the Social Democratic Party's president, resigned to become Neves' vice presidential candidate.

Neves, who has 50 years of political experience and is known for his skills as a mediator, was seen as the consensus choice of moderates over the ambitious, conservative and publicly unpopular Maluf.

Neves will take command of the world's fifth largest country at a time of moderate economic growth after three years of recession. He will face managing the developing world's largest foreign debt, now more than $100 billion, and inflation that has reached an annual rate of 220 percent and is still rising.

Preoccupied until now with constructing the broadest possible alliance in the electoral college, Neves has outlined his program of government only in general terms. Many politicians and diplomats here expect him to conduct a moderate administration that will attempt few major reforms and not fundamentally alter the military's economic policies of state-directed development.

During his campaign, Neves said he would "discipline" state spending while shifting more resources into social programs and seeking to increase basic food production for Brazil's millions of malnourished poor. He has pledged to negotiate a "social pact" with business and labor to fight inflation and spur development, but added that such a pact "will not demand any sacrifices by workers."

Neves today called inflation "the clearest manifestation of the disorder in the national economy" and promised, "we will confront it beginning the first day." He added that "we will not fall into the gross error of using recession as a deflationary instrument."

The various sectors of Neves' electorial coalition, which range from the far left to the moderate right, have proposed widely varying programs of government, and some analysists believe the new president's Democratic Alliance may soon split up.

Neves' own Brazilian Democratic Movement party has announced that it would back a "negotiated moratorium" on foreign debt payments. Neves, however, has said he will not support a moratorium and has appeared to accept the outgoing government's negotiations with banks this month on a long-term renegotiation of Brazil's foreign loans.