New Munster was an early original European name for the South Island of New Zealand, given by the Governor of New Zealand, Captain William Hobson, in honour of Munster, the Irish province in which he was born.
When New Zealand was separated from the colony of New South Wales in 1840 and established as a colony in its own right, the Royal Charter effecting this provided that "the principal Islands, heretofore known as, or commonly called, the 'Northern Island', the 'Middle Island', and 'Stewart's Island', shall henceforward be designated and known respectively as 'New Ulster', 'New Munster', and 'New Leinster'". These divisions were at first of geographical significance only, not used as a basis for the government of the colony, which was centralised in Auckland. New Munster referred solely to the South Island.
The situation was altered in 1846 when the New Zealand Constitution Act 1846 divided the colony into two provinces: New Ulster and New Munster. New Munster included the South Island and Stewart Island, plus the southern portion of the North Island up to the mouth of the Patea River. New Ulster consisted of the remainder of the North Island. These boundaries incorporated the Cook Strait settlements of Wellington and Nelson into one province, despite being on different islands. Each province had a Governor and Legislative and Executive Council, in addition to the Governor-in-Chief and Legislative and Executive Council for the whole colony. Early in 1848 Edward John Eyre was appointed Lieutenant-Governor of New Munster. In 1851 the Provincial Legislative Councils were permitted to be partially elective.