Firefighters arrived at the factory on Villiers Drive in Wendouree in Ballarat after a fire was reported at about 6.30am.
A man was pulled from the alight factory but died at the scene.
Two other men managed to evacuate the factory without injury.
Police have set up a crime scene and arson detectives will be examining the scene today, along with fire investigators.
Anyone with information about the fire is urged to contact police.
