Prime Minister Zenko Suzuki of Japan, brushing aside repeated U.S. appeals that Tokyo contribute more to Asian defense, declared yesterday that significantly higher Japanese military spending would cause the defeat of his government, opening the way to leftist rule that would endanger U.S. Japanese relations.

Coming on the eve of his visit to Washington and talks with President Reagan scheduled later this week, Suzuki's remarks seemed designed to buttress in advance his arguments against rises in Japanese defense spending. Increased military spending has been suggested to Tokyo with has been suggested to Tokyo with growing insistence by the Reagan administration and is expected to be the main source of disagreement in Suzuki's talks with U.S. officials now that Japan has agreed to restain its auto exports to the United States.

"Our people would not approve of it," he said on the interview program "Issues and Answers" (ABC-WJLA). "Once we do it, in the next election our Liberal Democratic Party will certainly lose it. We'll be thrown out of the seat of our government.

"On top of it, the opposition party, the foremost opposition party, the Japanese Socialist Party, being a socialistic party, wishing to take over the government, [is] joining hands with the Communist Party, and once this happens they would scrap [the] Japan-U.S. security treaty," he added, speaking through an interpreter. "This these oppositions have clearly enunciated in the past. This will upset the very basic, the bedrock of Japan-U.S. cooperation, security arragnements, that is."

Although rated unlikely in the current political atmosphere, Suzuki's prediction marked an unusually explicity rendition -- particularly to a U.S. television audience -- of an argument often raised by Japanese and, on occasion, even American proponents of resisting pressures from outside Japan for increases in Japanese military commitments.

It flies in the face of the repeated requests from the United States for higher military spending in Japan to increase Tokyo's role in the defense of Northeast Asia. The request date from well before the Reagan administration took office, but have been intensified by its emphasis on strengthening the military capacity of the United States and its allies against the Soviet Union.

Secretary of Defense Caspar Weinberger recently declared that he expects Japan to spend significantly more on its military. U.S. officials are reported to be specially interested in better Japanese antisubmarine and air defense capability.

The U.S. ambassador to Japan, former senator Mike Mansfield, has called on Japan to take up the slack in the U.S. 7th Fleet caused by movement of ships to the Persian Gulf and Indian Ocean. This was movement of ships to the Persian Gulf and Indian Ocean. This was specifically rejected by Suzuki last weekend in a meeting with U.S. correspondents in Tokyo.

In dismissing Mansfield's suggestion, Suzuki referred to provisions in the Japanese constitution limiting the role of the Japanese military to self defense. Because of these provisions, he said, any military moves "beyond our immediate territorial land and peripheral waters" would be barred.

He repeated this argument yesterday, saying: "For us to step out of this boundary in any military way, to possitively contribute to the stability of the world, is something beyond our ability under our constitution, and you cannot expect us to do that."

In addition, he said, Japan's neighbors still harbor fears dating from Japanese military expansion in World War II and, as a result, "they are naturally sensitive to Japan's defense capabilities."

Suzuki said the Japanese defense budget has increased by an average of 7 percent for the last few years -- a higher rate, he declared, that NATO defense budgets. Moreover, Suzuki argued, his government has been forced to cut back on spending for such items as schools and public health and therefore would find it impossible to defend raising defense spending at the same time.