A sixth branch in Devonport is undergoing consultation over whether its hours will also be cut.
A BNZ spokeswoman said it was constantly reviewing its branch network to make sure it was focusing investment where it could best serve the changing needs of its customers.
"Our customers are increasingly choosing BNZ's digital banking channels to fulfil their everyday banking needs and the decline in demand for in-store banking reflects this fact."
She said the bank's biggest store was not its Queen St branch but its website.
"Digital accounts for nine out of every 10 bank transactions."
The bank needed a branch presence but it could not sustain the same stores it had five years ago, she said.
BNZ's moves follow that of other banks.
Last year Westpac closed 19 branches in mainly rural areas and the ANZ also planned to cut six branches.
New Zealand First leader Winston Peters told the Northern Advocate that the BNZ's moves were about boosting profits and were bad news for older Kiwis who prefer face-to-face banking.
He said it was "another example of a foreign corporate's indifference to small-town New Zealand".
"It's not as though they are running short of money. Last year BNZ overall recorded a profit of $913 million.
"But like other Australian-owned banks in New Zealand such as Westpac, which shut 19 branches around New Zealand last year, they are interested only in making as big a profit as they can," he said.
Changes to BNZ branch hours
• Hours have already been reduced at Leeston (11am-4pm), Akaroa (10am-3pm), and Karori (1pm-4pm).
• Hours will be reduced in the next few weeks at Christchurch Hospital (10am-2pm), Dargaville (9am-12.30pm), Kaikohe (1pm-4.30pm), Reefton (11am-1pm, 1.30pm-3pm) and Cromwell (10am-3pm).
• BNZ is consulting with its Devonport staff about reducing the hours.
