Japan's renunciation of nuclear weapons and powerful military forces is not a "free ride" on the United Stares but an example to the whole world, Prime Minister Takeo Fukuda says.

"Japan is economically and industrially capable of equipping herself with very strong armed forces, even nuclear weapons, if only she desires. But we do not desire such things." the prime minister said in an interview. He is scheduled to be in Washington for talks with President Carter March 21 and 22.

Responding indirectly to American criticism that Japan spends less than 1 per cent of its gross national product on defense and is content to rely on U.S. protection. Fukuda stated: "For the time being we may give the impression of having a free ride, but the resources we have not been pouring into our defense we are contributing-and can contribute more-for economic development of the whole world."

Calling the need for global disarmament "the major challenge facing mankind in the future." Fukuda added "In this endeavor I think Japan's determination and position will prove a very valuable example."

Under the 1960 mutual security treaty, the United States is committed to come to Japan's aid, with nuclear weapons if necessary. In recent years various American officials have urged Japan to improve its military canability and bear a greater share of the burden for its own defense. In 1975, the then Defense Secretary James R. Schlesinger said the existing 265,000 man Self-Defense Forces were inadequate to defend the four main islands of Japan.

Fukuda advanced on eloquent defense in the interview of Japan's underlying pacifism. "Peace," he said, "is not only maintained by military might. I think in the final analysis peace is best maintained by a stable, happy life for people everywhere."

Admitting some inadequacies in the skeletal defense force, Fukuda said a gradual upgrading of quality would continue.

The planned withdrawal of U.S. ground forces from South Korea would have no impact on Japan's defense program, the premier said, because he was confident the United States would always take the need for military balance on the Korean peninsula into consideration. A gradual withdrawal over a long, long period of time would have no "adverse repercussions on japan." he said.

Japan has been heavily criticized by developing nations in Asis for not giving enough aid and Fukuda conceded that the amounts were too small. In 1975, Japan's economic assistance to developing nations was less than a quarter of one per cent of its GNP-well below the standards set by the 17 industrially advanced countries of the Organization for Economic Cooperation and Development. As a new prime minister, Fukuda was able to achieve only a slight increase in the current aid budget, he said, while promising "substantial improvements" next year.

A slender, balding figure, the 72-year-old premier spoke for almost an hour. He understands English, frequently nodding in understanding befor e the translation, but replied through an interpreter.

Fukuda carries his years casually. He poled a pencil into his shoe and flashed his characteristic elfin grin when he said that becoming prime minister last December brought him "headaches" every day."

Fukuda said his main concern in the forthcoming Washington meetings would center on possible steps by the United States, Japan and other countries to end "world economic confusion." An economic expert with an international outlook, Fukuda again aired his fears that recession could cause a global political crisis "if we just fold our arms and do nothing about it."