The dead gaur was found near Kunshorn forest plantation project inside the national park, he said.
Mr Theerapat said the cause of the animal's death was not yet known. It is the 19th gaur carcass found in the national park since early December.
Meanwhile, Kui Buri residents on Friday voiced their disagreement over the appointment of Suriyon Bhodhibandith as acting chief of Kui Buri national park, replacing Preecha Viriyaphan, who has been moved to an inactive post following the gaur deaths.
Mr Suriyon will also oversee the investigation into the deaths.
Local leader Narongsak Pipatsath-einthai, who is a kamnan in the district, doubted if Mr Suriyon was suitable for the post as the official had been found guilty by the Phetchaburi provincial court in March for destroying a wild elephant carcass without permission.
The court handed down a two-year suspended jail term to him.
The locals last month submitted a petition to Natural Resources and Environment Minister Vichet Kasemthongsri, asking him to review Mr Suriyon's appointment. But the petition fell on deaf ears, he said.