Rep. Norman Y. Mineta, D-Calif., the senior Democrat on the House Transportation and Infrastructure Committee, announced Monday he is leaving Congress to take a job with Lockheed Martin Corp.

In a press conference held outside his boyhood home in San Jose, Calif., Mr. Mineta, 63, said he will step down Oct. 10 to head Lockheed Martin's transportation system and services division, a group aimed at developing intelligent transportation systems. He will be a senior vice president based in Washington, D.C., a company spokesman said.The division is part of Lockheed Martin's information management systems group based in Teaneck, N.J.

"This is not a decision I take lightly. But for me I see this as a great new opportunity to build a better society," said Mr. Mineta, who has served in the House since 1975.

Based in Bethesda, Md., Lockheed Martin is one of the nation's largest defense contractors following a merger in March between Lockheed Corp. and Martin Marietta Corp.

Leaving more than a year before his current term expires, Mr. Mineta had been chairman of the Transportation Committee in the 103rd Congress.

As chairman, he played a major leadership role in producing legislation deregulating intrastate trucking. He was also vocal about the growing need for public and private investment in the nation's transportation infrastructure. But Mr. Mineta was unsuccessful in reaching a deal with Senate lawmakers to designate the National Highway System.

In prior years, Mr. Mineta had been a leading champion for shippers in legislative efforts to resolve the multibillion-dollar "undercharge" problem in the trucking industry.

A senior committee aide said Mr. Mineta would likely be replaced as leader of transportation Democrats by Rep. James Oberstar, D-Minn., who this year has played a role as a consensus builder in shaping the pending Ocean Shipping Reform Act of 1995.

In prior years, Mr. Oberstar, 61, had been an opponent of deregulation and advocated some reregulation of transportation industries. In the last Congress, he was a major opponent of bills to slash the Interstate Commerce

Commission and further deregulate interstate and intrastate trucking. Those bills - introduced and pushed with the active leadership of Mr. Mineta - were successful and signed into law.

The outspoken Mr. Oberstar is perhaps best known for his interest in aviation safety because of his years as chairman of the aviation subcommittee before the Democrats lost control of the House last fall.

Lately Mr. Oberstar has ridiculed the Clinton administration's proposals to privatize the air traffic control system or spin it off into a government corporation separate from the Federal Aviation Administration. Instead he has joined with Republicans in introducing a bill to make the FAA an independent agency, outside the control of the White House or the Department of Transportation.

Mr. Oberstar also favors efforts to lower federal limits on truck weights and lengths. Last year, he unsuccessfully introduced a bill to freeze those limits nationwide.