They handed in their letter to Deputy Education Minister Sermsak Pongpanit who later promised that he would try to solve all the problems by next week.
The Pheu Thai Party pledged in its election campaign last year to pay a starting salary of 15,000 baht to university graduates if it came to power.
However, the campaign caused confusion among school administrators when the Comptroller-General's Department in June told the public that the 15,000-baht salary would not apply to school administrators who had been hired as temporary employees.
Shortly after the report came out, school administrators under the Administration School Federation called on the cabinet to consider the matter. But no progress has been made to date.
Vitrapong Pumbunpak, head of the federation, who led the administrators, said school administrative staff were working in the public sector and had bachelor's degrees. As such they were entitled to the same 15,000-baht salary as other state employees.
Mr Vitrapong said the matter had been forwarded to the cabinet for consideration and the cabinet had pledged the decision would be known in August but no reply has been received.
"Several months have passed but there has been no clarification, only confusion," he said.
Mr Vitrapong said the federation had asked the cabinet to approve a minimum salary of 15,000 baht for school administrators and other school temporary employees with a bachelor's degree.
And those who have a salary of less than 9,000 baht a month would be given a subsistence allowance to lift their salary to 9,000 baht, he said.
"There are 14,532 school administrators countrywide and our salary is only 9,140 baht. We need an increase to boost job security," he said.
Besides administrative duties, Mr Vitrapong said that many school administrators had to teach students as well.
In order to prevent a shortage of teachers, he said the Education Ministry should open more quotas for assistant teacher positions and allow some school administrators with a bachelor's degree and three years' work experience to take exams for the positions.
Rangsan Maneelek, director of the Office of the Basic Education Commission's Policy and Planning Office, said he knew that some school administrators were asked to help with teaching duties because the ministry was facing a shortage of teachers in some small schools.