"I don't take offence from it," he said.
"I don't condone it but there are far worse cases [of vandalism] out there. There are some National ones with faces cut out and others around the country with terrible words and slogans on them."
Earlier this week police began an investigation after a hoarding on 15th Ave featuring National leader Bill English's was burned.
Mr Mitchell said he was made aware of the sign on Tuesday and it would be replaced.
"Every year people have a go at your signs. Some are down right disgusting but this one isn't so bad," he said.
"I think some people might find this funny."
Mr Mitchell joked that while he had not 'had enough whiskey' at the moment, he planned to have a glass on election night.
Another New Zealand First hoarding on Fraser St was also added to, advertising a message of 'Had enough? Of you'.
A Tauranga City Council spokeswoman said the council had not received any complaints about vandalised political signs.
However, the council had received complaints regarding the incorrect placement of between 5-10 election signs, she said.