WASHINGTON (AP) _ Members of Congress, anticipating Mikhail Gorbachev's summit visit here next month, on Thursday endorsed a resolution urging the Soviet Union to allow immediate exit of its citizens long prevented from joining husbands or wives in America.

The House Foreign Affairs Committee approved on a voice vote and sent to the floor the measure introduced by Rep. Connie Mack, R-Fla., representative in Congress of Anatoly Michelson, the longest separated in at least 15 pending U.S.-Sovie to get exit permission for Svetlana Braun and ''we've got to keep up the pressure'' in behalf of spouses still in the Soviet Union, said Rep. William Broomfield, R-Mich.

When Gorbachev meets President Reagan here in December, ''I hope we will use the occasion to talk about this subject,'' Broomfield said. ''I don't know of any subject as important.''

Mack told members about Anatoly Michelson, now 69, of Naples, Fla., whose wife Galina and daughter Olga were prevented from joining him after he decided three decades ago to live in the West.

Mack's office said the forthcoming Reagan-Gorbachev summit and conclusion of a U.S.-Soviet pact eliminating medium-range nuclear missiles make it a propitious time to press for quick solution of the pending divided spouse cases.

The superpowers ''are approaching conclusion of a major arms reduction agreement'' and the spirit of such an agreement should foster progress in human rights, says the resolution sponsored by Mack and more than 40 other Congress members.

The Soviet Union, as a participant in the 1975 Helsinki East-West agreements, is specifically obligated to promote ''the reunification of divided families and marriage between citizens of different states,'' it adds.

The resolution asks the Soviet government ''to give special consideration to cases that have remained unsolved for many years, the longest of whch is the case of Galina Goltzman Michelson and her daughter and grandson.''

It requests immediate exit permission to all others wanting to join spouses in America with their family members and lists 10 spouses: Yuri Balovlenkov, Viktor Faermark, Yevgeny Grigorishin, Elena Kaplan, Vladislav Kostin, Viktor Novikov, Pyatras Pakenas, Sergei Petrov, Leonid Scheiba and Andrei Zhitkov.