It may be a brand new baseball season, but they're still playing the same old game in the Japanese leagues.

U.S. bat manufacturers continue to strike out in Japan where they are pitched curves and sinkers by Japanese baseball groups preventing them from getting a handle on that big league baseball bat market.

After futilely slugging away, U.S. bat makers are calling a foul on the Japanese baseball leagues for refusing to certify foreign baseball equipment for use in their highly popular games.

The issue has been discussed by the Reagan administration and the Japanese government for several months. When the Japanese government announced this year that it was taking 99 steps to open its markets to foreign goods, the Japanese Ministry of Education issued guidance to all of the private sports associations to approve foreign products, according to the U.S. Trade Representative's Office.

But the U.S. sporting goods manufacturers said they have yet to make it to first base because they haven't made a single sale. The Japanese are balking and using delaying tactics such as sending certification papers to the American firms written in Japanese, and several points on their applications had to be clarified, according to Maryanne Mascolino-Esser of the Sporting Goods Manufacturers Association.

The league, which isn't government-controlled, hasn't yet said officially that it will accept the American bats, she said.

What's at stake is scoring in the $30 million Japanese baseball bat market, which consists mostly of aluminum bats used to hit rubber balls in the Japanese-style game. Japan has 1.2 million amateur players on 61,551 teams, Mascolino-Esser said. The games often start at 8 a.m. and run until midnight, she added. The bat makers also want to build up their trade names in Japan with succeeding generations of Japanese baseball fans.

Several years ago, American bat manufacturers such as Hillerich & Bradsby Co. Inc., which produces the Louisville Slugger and which has annual sales of $38 million, started making the lightweight bats, which retail from $18 to $40, Mascolino-Esser said. About six months later, the Japanese began manufacturing their own aluminum bats.

A Japanese Embassy spokesman said the certification process was started after a spectator at one of the games was injured by a metal bat that broke during play. However, Mascolino-Esser said the bat was Japanese-made. The embassy spokesman said he didn't know what kind of bat it was.

The situation is not controlled by the government because the sports leagues are privately operated, the embassy spokesman said.

"Until we are able to sell that first bat, we're going to keep pushing," Mascolino-Esser said. "That's what keeps the factories employed . . . Those export sales and sales overseas are an important plus, particularly in times like these."

"I expect it will be resolved very soon," said Donald Abelson, director of technical trade barriers at the office of the U.S. Trade Representative. He said he thinks the U.S. bats eventually will sell overseas. "Any day now," Abelson said, American bat makers will be able to "play ball."