PRIME MINISTER Zenko Suzuki of Japan reorganized his Cabinet yesterday, apparently in the hope of reducing the friction with the United States over trade. Mr. Suzuki is only the latest in a long succession of Japanese politicians and diplomats to try to decide how seriously to take the perennial American complaints about a trade imbalance that is now very large and getting larger. Americans themselves give two very different answers.

American bankers and economists tend to reply that the trade deficit with Japan is not in itself terribly significant. A lot of the world's trade is triangular, and it's the total trade balance with all countries together that counts. For the past couple of years, this country's total trade deficit has been offset by the massive earnings of American foreign investments, creating a satisfactory balance.

But American manufacturers, and American congressmen, usually take exactly the opposite view. Their companies and their constituents are under fierce competitive pressure from Japanese products. It simply isn't fair, they argue, to allow Japan almost unlimited access to the huge American market when American goods have such difficult and conditional access to Japan's.

The question of competition is worth pursuing. Even if both Japan and the United States were totally open to each others' goods, Japan would continue to run a substantial trade surplus. Japan must import all its oil, for example, and must earn the dollars to pay that bill. But the Japanese market is not totally open. By no means all of the barriers to imports are imposed by government policy. Sometimes it's a matter of deliberately dilatory resistance by Japanese officials at low levels. Sometimes it's the idiosyncracies of the Japanese distribution system. Sometimes the American product is simply not well adapted to the Japanese consumer. It's open to question, for example, whether the American automobile companies could ever sell many of their cars in Japan. But there's no doubt at all about the difficulties of clearing a foreign car for sale in Japan.

An even more sensitive issue arises when the Japanese government appears to be organizing an industrial monopoly to compete abroad. Within the Reagan administration there is rising concern about the Japanese government's success in promoting the industry that makes integrated circuits -- the silicon chips that are the nervous system of a computer -- and ships them here.

Mr. Suzuki and his new Cabinet would probably be correct in concluding that American policy is not terribly sensitive to trade imbalances themselves, even when they are large. But it is quite sensitive to trade practices that are, in the American tradition, unfair -- and there, Japan is risking American reactions that can be dangerous to the economies of both countries.