Most signatures are from New Zealand, but others are from Australia, Britain, Ireland, the United States and Iraq.
Wendy Belworthy, of New Zealand, said in a comment that a courthouse should not be put in an old school. "The facility would be much more productive used as an alternative education facility to reduce the need for courthouses in the first place."
Nadia Olliver, who grew up in a house that backed on to the former school but now lives Australia, said the plan was a disgrace. "The area is quiet, safe and a great place to grow up," she said.
The petition's goal is 1000 signatures and is targeted at Masterton District Council and Mayor Garry Daniell.
An independent planning commissioner will make a decision based on the application for resource consent and submissions received.