Japan's program to increase the value of the yen has created hardships in the Japanese economy and caused the owners of some small businesses to commit suicide, a leading Japanese industrialist said here yesterday.

Norishige Hasegawa, director of Sumitomo Chemical Co. Ltd., said his firm's overseas sales have declined as a result of the higher value of the yen, which makes Japanese products more expensive in overseas markets.

Nihachiro Hanamura, chairman of Japan Air Lines Co. Ltd., said Thursday, moreover, that the Japanese economy "has begun to show some signs of a slowdown . . . and there is increasing fear of a downturn."

The value of the yen has increased by about 23 percent against the dollar in the past 10 months. This is partly as a result of a Japanese government effort to bring its currency more in line with those of the other major trading nations.

The dollar hit a seven-year low yesterday againt the yen, which rose to 195.60 to the dollar in New York markets amid speculation that Japan would lower its interest rates.

"Many Japanese industries are already having trouble because of the appreciation of the yen," Hasegawa told reporters at a luncheon for officials of Japan's largest and most influential business organization, the Keidanren.

He said auto and steel manufacturers are complaining, "but they have lots of reserve power and will be able to cope."

The heaviest burden has fallen on small- and medium-sized industries such as makers of stainless-steel silverware that depend on foreign sales for their survival.

"There already have been some tragic events such as suicides," because the higher yen has forced some companies into bankruptcy, said Hasegawa, who is an executive vice chairman of Keidanren.

For this reason, he supported as a "social policy aimed at the poor" a program of low-interest loans for small businessmen hurt by the increase in the yen.

U.S. Trade Representative Clayton Yeutter, however, told Japanese officials last week that the program undermines the reason for increasing the value of the yen and is illegal under international trade rules.

A stronger yen and weaker dollar are a prime element of President Reagan's policy to ease record U.S. trade deficits with Japan.

Hasegawa said the rise in the value of the yen will be good for Japan in the long run.