The ruling by the Appeals Court was seen to uphold earlier ruling by the Criminal Court on May 29, 2014 throwing out the lawsuit against the National Council for Peace and Order under the leadership of Gen Prayut Chan-o-cha.
The groups, which was led by one student activist Sirawich Seritiwat, said they will petition the case to the Supreme Court.
Four other members of the military junta accused of treason are former Navy chief Admiral Narong Pipattanasai, former Air Force chief Air Chief Marshal Prajin Juntong, former Armed Forces chief Gen Tanasak Patimapragon, and former national police chief Pol Gen Adul Saengsingkaew.
The Appeals Court cited Article 48 of the interim charter that grants amnesty for the military junta in dropping the lawsuit against them.
Activists students filing treason charges against the military top brass include Baramee Chairat, Krit Saengsuk from Khon Kaen university.