Bhausaheb Sonawane, a resident of Pawan Nagar hanged himself inside a tin shed, erected for the Kumbh Mela, at the Ambad police station in the wee hours, the station's in-charge Madhukar Kad said.
The incident came to light after some police personnel saw Sonanwane hanging, the officer said.
Nashik Police Commissioner S Jagannathan and other senior officials rushed to the spot to take stock of the situation.
The reasons behind the constable taking the extreme step are not yet clear. However a four-page letter was found in his pocket, police said, adding investigation is underway.