TOKYO, NOV. 21 -- Fifty-two years and 50 weeks after the event, Japan's government finally apologized today for failing to break off diplomatic negotiations before launching the sneak attack on Pearl Harbor that pulled the United States into World War II.

"There can be no excuse," the Foreign Ministry said, for Japan's delay in delivering a message to Washington on Dec. 7, 1941, that it would negotiate no longer. The official apology was prompted by the routine declassification of a new batch of documents relating to that fateful day.

But today's apology for Japanese diplomats' "deeply regrettable" conduct on Pearl Harbor Day was not addressed to the United States, the victim of the attack. Rather, said Foreign Ministry spokesman Terusuke Terada, "the statement was directed to the people of Japan."

Why does the government feel a need to apologize to its own people for deceiving another nation a half-century ago?

The answer involves the generalized concept of shame in Japanese society, and the particular sense of shame many Japanese feel about the beginning of World War II.

In a country where people are defined by the groups they belong to, anyone who does wrong is perceived to be causing shame for other members of his group -- his family, his company, his alma mater. If a factory worker, for example, robs a bank, the bank is not the only victim. All the other employees of the robber's factory suffer from the crime as well, because of their association with a thief.

The Japanese have a word for it: meiwaku, which can mean the trouble and shame you cause for friends and family if you do wrong. For centuries, the need to avoid meiwaku has served as a powerful restraint on bad conduct; it is a key reason why this crowded society is so polite, peaceful and free of crime today.

In Japanese history books, the conduct of Japan's diplomats in Washington on the eve of Pearl Harbor is treated as a major source of shame for the entire country. That is what prompted the Foreign Ministry's belated apology today.

The diplomatic question at issue is separate from the propriety of the air raid itself, which killed 2,400 American soldiers and sailors. The Japanese people are still deeply conflicted on that point.

Some argue that a war between Japan and the United States was inevitable, and thus the surprise attack on the U.S. fleet was a legitimate act of war. Others here say it was morally wrong for Japan to start a war no matter what the circumstances.

In 1991, on the 50th anniversary of the attack, the prime minister of Japan issued an apology, of sorts, to the United States, expressing "deep remorse ... that we inflicted an unbearable blow on the people of America and the Asian countries."

But last year, politicians here canceled a scheduled visit by Emperor Akihito to the Pearl Harbor memorial. Japanese officials explained that Americans would expect an apology if the emperor went to Pearl Harbor, and that this might cause political problems at home for Japan's elected government.

No matter how people feel about the actual raid, however, there is a strong sense of shame here about Japanese diplomacy in the last weekend before the attack.

In the fall of 1941, the United States and Japan tried one last round of negotiations to resolve their angry dispute over Japanese aggression against China. While the talks were going on, a Japanese naval task force secretly sailed for Hawaii to attack Pearl Harbor.

On the morning of Dec. 7 -- or Dec. 8, on Japan's side of the international date line -- Japan's Foreign Ministry sent a final message to the State Department. It was supposed to be delivered at 1 p.m. Washington time, just 25 minutes before the raid was to begin. With characteristic vagueness, the cable did not clearly declare war or threaten attack. It said Japan "cannot but consider that it is impossible to reach an agreement through further negotiations."

Even the Japanese diplomats at the embassy in Washington did not understand this to be a warning of imminent attack. They took their time in typing an English version and did not deliver the message to the U.S. side until an hour after Pearl Harbor had been bombed.

Among the documents released today are letters from Japanese diplomats in Washington saying they were amazed to hear reports on the radio that their nation had attacked Pearl Harbor.

Although the tale of the delayed message is a staple of Pearl Harbor movies, it is not widely known among Americans. In Japan, though, it is conventional wisdom that the failure to deliver this vague message as planned, 25 minutes before the attack, is the reason that Americans to this day do not trust the Japanese in negotiations.

"The delay in delivering that announcement," the national newspaper Asahi Shimbun said today, "sparked a widespread belief among the American people that the Japanese are sneaky. Long after, the feeling lingers, and even in economic disputes it has a profound impact on Americans' deep distrust of Japan."

The issue resurfaced today because documents concerning the tardy cable were included in some 16,000 pages of diplomatic papers made public as part of a declassification program at the Foreign Ministry here.

Since it was easy to predict that newspapers would give the issue banner headlines -- as they all did -- Foreign Ministry officials decided to issue an apology today to the people of Japan for this 50-year-old meiwaku.

"Of course, Japan should apologize to the U.S., too," said sociologist Katsusuke Suenaga. "But in Oriental societies, particularly Japan, the group you belong to disciplines your conduct. Since the Foreign Ministry was guilty of misconduct here, it is entirely natural that it would apologize to the people of Japan for causing shame."