Mr Upton said he wasn't concerned about the protesters.
"People should come and have a look and make up their own minds ... We try and do our utmost to make everything safe for the horses, and all the animals are being treated well."
Mr Upton said if people didn't like something they shouldn't go. "I'm not keen on golf so I wouldn't go to a golf tournament."
The protesters could be good for the event in that they would attract attention. Mr Upton said the event this Saturday and Sunday would be run as two separate rodeos with the same events on both days.
Mr Upton said cowboys would come from all over New Zealand, from as far south as Invercargill and Wanaka, to the top of the North Island.
There were usually 250 to 300 entries each day. The rodeo's traditional events include saddle bronc, barrel racing and the bull ride.
The rodeo also includes roping, bareback riding and bull riding. The Mid Northern Rodeo had been going since 1965.