Robert E. L. Johnson, a retired board chairman of Woodward & Lothrop who was active in the civic affairs of the District of Columbia for many years, died of cancer Thursday at Anne Arundel General Hospital, in Annapolis. He was 71.

Mr. Johnson, who had lived in Gibson Island, Md., since his retirement in 1964, joined Woodward & Lothrop in 1948 as an assistant vice president, and was instrumental in the store's decision to open its Chevy Chase branch and expand into the suburbs.

A native of Philadelphia and graduate of Chestnut Hill Academy and Swarthmore College who attended the Harvard Business School, Mr. Johnson began a career in merchandising in 1929 when he joined Strawbridge and Clothier's there.

Mr. Johnson remained with the Philadelphia firm until the outbreak of World War II, when he joined the Navy as a lieutenant commander. He spent the war years in Washington and returned to Philadelphia after his discharge.

Mr. Johnson's rise through the Woodward & Lothrop corporate hierarchy was a swift one. Eight years after joining the firm he was named an executive vice president, a year later, in 1957, he was named chief executive officer, and two years after that he was named chairman of the board, a post he held until his retirement.

During his years in Washington, Mr. Johnson also served for a time as chairman of the United Givers Fund Drive and the Red Cross residential drive.

Mr. Johnson, who served as a director of the Federal Reserve Bank of Richmond, Va., also gave his time as a member of the boards Suburban Hospital and the Landon School, in Bethesda.

Mr. Johnson is survived by his wife, Mary, of Gibson Island; a daughter, Anne Clark, of Barrington, R. I.; a son, Robert E. L. Jr., of Bethesda; two brothers, Howard C., of Portland, Me. and George K., of Plantation Key, Fla.; and seven grandchildren.

The family asks that expressions of sympathy be in the form of contributions to the American Cancer Society.