Once President Reagan signs a bill just enacted by Congress, the home of the late black leader Mary McLeod Bethune off Logan Circle near downtown Washington will become a national historic site.

The Senate voted final passage late Wednesday to legislation that earlier had cleared the House.

In addition to designating the Bethune home -- called "Council House" -- at 1318 Vermont Ave. NW, the measure directs the Interior Department to make agreements with the National Council of Negro Women to aid in restoring and maintaining the place as a museum and archives. The council owns the home and has its headquarters there.

The legislation, sponsored in the two congressional chambers chiefly by Sen. John W. Warner (R-Va.) and Del. Walter E. Fauntroy (D-D.C.), authorizes a $100,000 outlay to help restore the site.

Warner said he became involved with the project when he was chairman of the national bicentennial commission in 1976. Under the legislation, the Bethune home will become affiliated with the National Park Service, which will be responsible for preservation and have access. The building's ownership will be kept by the women's council.

The District of Columbia already had designated the Bethune home an historic landmark under a category that "should be preserved, if practical."