Martin Shivnan, 56, special asistant to the secretary of the World Bank, died of acute myocarditis Wednesday in Wellington, New Zealand, where he was on an official mission. He lived in Washington.

Mr. Shivnan, who joined the World Bank in 1963 as an economic editor, became assistant to the secretary in 1970 and later was named special assistant.

He was born in Manchester, England. In 1942-44, he was a junior partner in the South Lancashire News Agency, a free-lance organization. He then worked for four years as a coal miner under England's National Service program.

He earned a degree in economics from Manchester University in 1951 and joined the Western Daily Press as an industrial and economic correspondent. He also was an economic correspondent with the Reuters Agency in London and with The Financial Times there before joining the World Bank.

Survivors include his wife, Barbara, and three daughters, Sally, Helen and Lucy, all of Washington; another daughter, Jane Marks of London, and two stepbrothers, Anthony and Jim Diffley, also of London.

The family suggests that expressions of sympathy be in the form of contributions to Catholic Charities or to Independent Living for the Handicapped, both in Washington.