According to an embodiment, a process apparatus performs processing on a byproduct generated in a reaction of a raw material including silicon and a halogen element or in a reaction between a raw material including silicon and a raw material including a halogen element. The apparatus includes a process liquid tank, a processing tank, a supplier and an exhauster. A process target member including the byproduct is introduced into the processing tank. The supplier supplies the process liquid from the process liquid tank to the processing tank and performs processing on the byproduct with the supplied process liquid. The exhauster exhausts a gas generated by reaction between the process liquid and the byproduct from the processing tank.