From 1976 to 1979, Chirayu was the dean of the faculty of economics of the government-run National Institute of Development Administration (NIDA). Chirayu became Minister of Industry under Prime Minister Prem Tinsulanonda in 1985, and Minister to the Office of Prime Minister one year later. After he had taken a stand for a controversial tantalum factory in Phuket Province that was burnt down by furious locals who were afraid of hazardous wastes, Chirayu was confronted with allegations of corruption, that could however not been proven.