TOKYO -- The good news is that the supercautious Bank of Japan is buying dollars without compensating for the effect on the Japanese economy by otherwise tightening money. The bad news is that, simultaneously, senior government officials call for draconian U.S. budget restraint in the face of what they expect to be a necessary American recession.

In short, the self-confident government of this economic superpower is no less confused about the global crisis than its counterparts in Washington. As of now, the economic advice that Noboru Takeshita, the new prime minister, will carry to Washington in January proposes American austerity as the antidote to the stock market plunge.

Replacement by a more typical Japanese for the dynamic Yasuhiro Nakasone has not changed economic policy. While the dollar and the Tokyo Stock Exchange fell in tandem last week, Takeshita was busy harmonizing demands by the ruling party's rival factions for Cabinet slots in the new government.

Policy is maintained by the Finance Ministry's renowned bureaucracy. Kiichi Miyazawa, one of Takeshita's rivals for the post of prime minister, is staying on as finance minister as well as becoming deputy prime minister. In Japan, governments change with scarcely any transition needed.

The continuing though unannounced policy is to keep following the Louvre agreement and support the dollar at the 140- to 150-yen range. As the dollar plunged last week, commercial bankers in Tokyo concluded that the range had slipped to a lower level of 135 and would fall still lower, to 130.

Senior finance officials vigorously denied that to us. But whatever the range, it is undisputable that the industrial nations are engaged in a major effort to prop up the dollar. U.S. officials have reassured their Japanese counterparts that published reports saying Washington wants a free fall in the dollar are totally false.

The new element is the Finance Ministry's confidence that the central bank, traditionally obsessed with inflation, will not be so spooked by the expansion of Japan's money supply caused by buying dollars that it will squeeze the domestic economy. The government does not want the embryonic economic boom here imperiled by either a 120-yen dollar crippling exports or Bank of Japan-type money.

That attitude contrasts with the austere view of what the Reagan administration should do domestically. In private conversation with us, economic policy-makers took the view that an American recession is not only inevitable but probably desirable.

In fact, one senior official expressed the view that a recession's likely reduction of the trade deficit -- because recession-struck Americans cannot buy so many Japanese cars -- is not all bad. ''It is better that this happen than a {protectionist} trade bill be passed,'' an important bureaucrat told us.

At the same time, these officials belittle a $23 billion budget fix as insufficient and insist on a major U.S. tax increase. Tokyo in effect is proposing U.S. action that would deepen the pain felt by Americans and extend it to the Japanese.

The austerity formula may reflect diminished confidence in U.S. economic policy-makers by the Japanese. They privately think Treasury Secretary James A. Baker III suffers from the absence of his former deputy, Richard G. Darman. They believe the Federal Reserve Board's pre-crash discount rate increase was a blunder, and are baffled by Chairman Alan Greenspan's following the hike with a statement declaring there was no inflationary danger.

Takeshita will not be nearly that blunt on his first visit to Washington as prime minister. He is being advised by colleagues to stress greater cooperation in the Persian Gulf. Behind such diplomatic pleasantries, however, is Japan's irrational belief that the United States deserves and needs hard times to cure the rest of the world.