An unknowing Stoke Lotto Powerball player carried around a $4 million prize winning ticket around in her handbag for nearly a month, before finally checking the ticket this week and realising she was a big winner.

The winning Powerball ticket was sold at Stoke New World and is worth a total of $4 million with $3 million from Powerball and $1 million from Lotto First Division.

The woman, and her family, are shocked by the big win. "I even shed a few tears at the Lotto counter when the lady checked my old tickets and First Division Winner flashed up. It was such a surprise.

"Apparently the local community and all the staff at the Stoke New World were speculating about who the missing winner could be - and all this time it was me," said the woman.

"I just chucked the ticket in my handbag with about four other old tickets, and never thought that I could have won the big one.

"It is not even a particularly nice handbag, just an old battered one that I have had for years. It might be time to buy a new one now," she said.

The family plan to upgrade their house and do some travelling with their windfall. "We also want to help out family members," they added.

NZ Lotteries' Chief Executive Todd McLeay says it is very unusual to have a big winner claim this long after a major prize is won.

"We are just glad this ticket got found and checked, rather than ending up buried in the bag for longer. It always great to unite a prize winner with their winnings," he said.