He told the Herald the error must've occurred during the design process, as it had been spelled correctly when he approved it.
"Obviously, it's not the sort of thing you want to do, it's not the sort of thing I would want to put in an ad, and the original proof that I approved didn't have that mistake," he said.
Simmons said he had already contacted the party's design team, who had fixed the error on their Facebook ads. No other advertising had misspelled the electorate, he said.
"We are mostly a volunteer-run organisation, so mistakes do happen."
He earlier told the Herald the TOP party wanted to double the price companies pay for emitting carbon and use that money to get more electric vehicles on the road.
By raising the price of carbon to be $60 a tonne, Simmons said, the roughly $1 billion a year raised would be used to implement a raft of environmentally friendly policies.
This included making the country's housing stock and businesses more energy-efficient and well as increasing urban density, which would allow more efficient use of public transport.
"Our houses have been described by some as 'wooden tents'," Simmons said.
The policy would have a real impact on the health and wellbeing of many New Zealanders, as well as putting more money in people's back pockets.
It follows National candidate Simon Bridges' blunder earlier this week, when he handed out piles of fliers that had his name spelled wrong.
The flyers, inviting Tauranga locals, where Bridges is the local MP, to various street corner meetings on the weekend instead invited them to see "Simon Brigdes".
The ousted National party leader shrugged off the blooper, telling TVNZ he had "a feeling people knew what name we intended."
"Grassroots politics isn't always perfect but it is always real," he told TVNZ.