Chalard Vorachat, a former Democrat Party MP, arrived at Bangkok's Ratchada Criminal Court with his lawyer on Tuesday morning to file a case against seven members of the National Council for Peace and Order (NCPO), 20 permanent secretaries and the judge advocate general.
The 71-year-old retired air force officer alleged they broke the law in declaring martial law and seizing power from the government.
"Martial law can be imposed when the country is at war. It can also be imposed in specific areas where violence erupts," he said. "The military acted without seeking royal endorsement and approval from the cabinet first."
The junta could summon him to report to the NCPO but he would not comply, he said.
He would be staging a hunger strike outside parliament should they decide to arrest him, he said.
The retired pilot officer said he had already been fasting for 19 consecutive days and would end his hunger strike when an election date is announced.
"If the country still doesn't have an elected prime minister I will (continue my) strike until I'm dead."
Mr Chalard has staged hunger strikes seven times since 1980, most of them were politically related. In his latest protest, he has been taking only water and honey.