An army spokesman, in a statement to the Israeli public radio, said the rocket exploded in a town in the Western Negev but caused no human casualties nor material damage.
No Palestinian group announced responsibility for the firing of the rocket.
This is the seventh rocket to be fired from Gaza towards southern Israel in 10 days, when the Palestinians announced commitment to a truce.
Israeli defense minister Ehud Barak, few days ago, threatened to retaliate against the rockets' attacks.
Palestinian gunmen fire rocket against S. Israel - army