Guy R. Justis, 68, director of the American Public Welfare Association here from 1964 to 1973 and a retired Social Security Administration officer, died of cancer Tuesday at Suburban Hospital in Bethesda.

While serving as director of the APWA, a national association of individuals and agencies engaged in local, state and federal public welfare programs, Mr. Justis also was a consultant on aging to the secretary of Health, Education and Welfare.

He joined the Social Security Administration's Bureau of Supplemental Income in Chicago in 1974 and served as state relations officer and administrator until his retirement in 1977.

Mr. Justis began his career in 1934 as a district supervisor for the Colorado Department of Public Welfare and served as the department director from 1954 to 1964. He also was an administrative consultant to the APWA from 1947 to 1952.

During the World War II, he served in the Navy in the Pacific theater.

He was born in Topeka, Kan., and earned bachelor's and master's degrees in social work from the University of Denver in Colorado.

Mr. Justis lived in Kensington. He served on the Advisory Council on Public Welfare from 1964 to 1966 and was a member of Rotary International and the Church of Jesus Christ of Later-day Saints in Kensington.

Survivors include his wife of 43 years, the former Ardis C. Larson, of Kensington; two sons, Richard, of Laramie, Wyo., and Robert, of Lincoln, Neb.; a daughter, Joan J. Shaw of Camp Hill, Pa., a sister, Beth Steahl of Denver; a brother, Wayne, of Pacific Palisades, Calif., and 13 grandchildren.