"It is unusual and irresponsible for a business owner not to assist with an investigation -- particularly in a case that, as Judge Burnett emphasised today, involved the safety of children."
WorkSafe said Gerritsen's trading entity, Event Fun Unlimited, was operating the Mammoth Slide at the A&P Show in February when it collapsed.
WorkSafe said several children fell from the top platform, a height of 12m.
Six children were taken to hospital because of their injuries and one who fell from the top of the stairs had ongoing problems with a minor knee injury.
WorkSafe said Gerritsen was today found guilty of one offence under the Health and Safety in Employment Act at Hamilton District Court.
He was fined $115,000.
In September, Gerritsen told the Herald he had a problem with the investigation and claimed the charge resulted from a "five-minute meeting" with WorkSafe.
He also claimed WorkSafe would not return his calls.
He wouldn't comment on why the inflatable slide collapsed but said the "children weren't badly injured and were back at the show later on".