Japan, in an effort to cut its giant trade surplus, has bought four more Western artworks, for a total of 490,140,000 yen ($2.3 million), it was announced today.

The Japanese cultural affairs agency said the four artworks are "Le Concert" and "Le Couple" by Marc Chagall; "Portrait of a Man," an oil painting by Belgium's Rogier van der Weyden; and a modern art object, "Solstice," by Robert Rauschenberg of the United States.

"Le Concert" and "Le Couple," bought for $429,300 and $375,600 respectively, will be displayed at the Tokyo National Museum of Modern Arts while "Portrait of a Man," $1.4 million, will be shown at the National Museum of Western Arts, also in Tokyo, the agency said.

"Solstice," valued at $220,400, will be put on display at the National Museum of Arts in Osaka, southwestern Japan, it said.

The Japanese government earmarked $4.15 million for the art-buying in fiscal 1978 and the agency has purchased a total of 13 art works, including "Vers Sortie de Jas de Buffen" by French impressionist Paul Cezanne; "Comedien et Enfant" by Spanish cubist Pablo Picasso; and "Lot Verlasst Sodom mit seiner Familie" by German humanist Peter Paul Rubens.