The quarantine, which restricts non-essential workers from leaving their homes apart from to buy groceries or medicines, has seen the South American country's streets virtually emptied, while its major grains industry has faced some disruption.
The tough measure was initially until the end of March. It will now be in place until the end of the Easter Holy Week, Fernandez said, which would mean it would be lifted on April 12, Reuters reported.
"We are going to extend the quarantine until the end of Easter. What do we aim to achieve? To keep the transmission of the virus under control," he said in a televised message.
Fernandez added that the initial results of the compulsory isolation since March 20 looked "good".
The country has recorded 820 coronavirus cases with 20 deaths, although the increase in cases has shown some signs of slowing in recent days.