Outgoing U.S. Ambassador James D. Hodgson said he believes "a certain amount" of rearming would be good for Japan but that American public opinion does not permit Washington to advocate it.

Hodgson, who resigned last month after 2 1/2 years as envoy to Tokyo, said he believes "it is not wise for a nation economically strong to be as militarily weak" as is today's Japan. But despite low-key suggestions in 1975 by then-Secretary of Defense James R. Schlesinger that Japan upgrade the quality of its existing "self-defense forces," Hodgson said, it is not U.S. policy to push Tokyo to expand its military.

Hodgson blamed the U.S. inactivity in part on "a big misimpression" that militaristic forces in Japan are threatening a major rearmament in that country.

"The U.S. concern should be the absolute unwillingness in Japan to consider arming even to the extent of handling their own self-defense," he said in an interview with editors of The Washington Post.

As a first step, Hodgson suggested a gradual increase in Japanese air forces and augmentation of Japanese ability "to stop or contain invasion forces."

The former envoy said it is difficult even to discuss such increases in Japan, which is barred by its postwar constitution from maintaining an army, navy or air force, and whose "self-defense" establishment consumes less than one-tenth of 1 per cent of national income.

Japan's principal security concern at the present time arises from the expected withdrawal of U.S. ground troops from neighboring South Korea. Hodgson said the Japanese would be "deathly afraid" of a shooting war between South Korea and North Korea after the removal of U.S. troops.

In order to stabilize the Korean situation, any withdrawal of U.S. ground troops should be gradual and take place after careful consultations with both Japan and South Korea, Hodgson said. (This is Carter administration policy.)

In addition, Hodgson suggested that the United States send an additional air wing to Korea or dispatch a new weapons system there to demonstrate to North Korea that the U.S. security commitment is undiminished.

Hodgson also suggested "some conversation" with China and the Soviet Union, which are the allies of North Korea, so that a U.S. troop withdrawal would not be misinterpreted.

Hodgson, a former Secretary of Labor and a former vice president for labor relations of Lockheed Aircraft Corp., said that if the Korean cutback is handled deftly, the United States and Japan should have four to five years without major difficulties between them.