John S. Backman, 72, a retired official of the Defense and Army departments who specialized in financial matters and procurement contracts, died of cancer Saturday at his home in Arlington.

Mr. Bachman began his government career as an Army officer in World War II. He was assingned to the Army's office of finance and was deputy chief of the advanced payments and loan branch with the rank of colonel at the time he left the service in 1946.

In 1948, he joined the newly-organized Department of Defense and became director of contract financing under the comptroller in the office of the secretary of defense. He also worked for the Department of the Army. He was director of contract financing in the office of the assistant secretary of defense for installations and logistics at the time of his retirement in 1971.

Mr. Bachman was born in Bristol, Tenn. He grew up in Cincinnati, Ohio, graduated from the University of Cincinnati and earned bachelor's and master's degrees in law there. He practiced law in Cincinnati for 10 years before beginning his World War II military career.

Survivors include his wife, Catherine R., of the home in Arlington, three daughters, Mary Wright and Elizabeth McIntire, both of Washington, and Josephine Stevenson, of Seattle, Wash., a sister, Dr. K. D. Bachman, of Falls Church, Va.; two brothers, Dr. Landon D., of San Francisco, and Nathan D., of Cincinnati, and four grandchildren.