The incident was reported around 1:30 PM. The body of Constable M K Roy (30) was found hanging at the forces' unit lines in the museum complex near the India Gate, officials said.
The Central Industrial Security Force is tasked to secure the complex and Roy was posted as a washerman of the said unit.
"A Court of Inquiry has been ordered to ascertain the reasons behind Roy taking the extreme step. Police have registered a case in this regard," they said.