Rebels of the People's Revolutionary Party of Kangleipak (PREPAK) tossed the grenade at Chief Minister Okram Ibobi Singh's residence in the state capital Imphal late Tuesday, a senior police official told AFP.
"The grenade exploded inside the campus of the chief minister's residence, but luckily no one was injured," he said.
Singh was in New Delhi at the time of the attack.
PREPAK, an outlawed rebel group fighting for an independent homeland for the majority Metei community in the state of 2.4 million people, claimed responsibility for the attack.
Singh has survived two previous assassination attempts by rebels.
In May, militants ambushed his convoy. He escaped unhurt, but a paramilitary commando and a rebel were killed in the encounter.
In 2003, militants killed three of the chief minister's security guards in another ambush on his convoy.
There are some 19 rebel groups active in Manipur, which borders Myanmar. Their demands range from secession to autonomy and the right to self determination.
More than 10,000 people have been killed in the insurgency in Manipur in the past two decades.

Copyright AFP (Agence France-Presse), 2006