Sarsar had in recent months been pushing hard for the holding of long-awaited municipal polls.
"Chafik Sarsar announces his resignation" Wataniya announced in a breaking news alert.
AFP was unable to immediately reach Sarsar. An employee of the electoral commission refused to comment.
Sarsar and the commission were praised for their organisation of legislative and presidential elections in 2014, following the revolution that toppled longtime dictator Zine El Abidine Ben Ali.
Sarsar had in recent months been pushing hard for the holding of long-awaited municipal polls, which after a series delays were finally set for December 17.
Tunisia, which set off the Arab Spring revolutions with its 2011 overthrow of Ben Ali, has been hailed for a relatively smooth democratic transition since the revolution.