Kim lies in state a few floors below his father, national founder Kim Il Sung, in the Kumsusan mausoleum, the cavernous former presidential palace in Pyongyang. Kim Jong Il was presented lying beneath a red blanket, a spotlight shining on his face.
Wails echoed through the hall as a group of women sobbed into the sashes of their traditional dresses as they bowed before his body.
The hall bearing the glass coffin was opened to select visitors for the first time since his death.
North Korea also unveiled Kim's yacht and armoured train, where he is said to have died. Among the personal belongings featured in the mausoleum are the parka, sunglasses and pointy platform shoes he famously wore in the last decades of his life.
North Koreans paid homage to Kim and basked in the success of last week's launch of a long-range rocket that sent a satellite named after him to space.
The launch, condemned in many other capitals as a violation of bans against developing its missile technology, was portrayed not only as a gift to Kim Jong Il but also as proof that his son, Kim Jong Un, has the strength and vision to lead.
The elder Kim died last December 17 from a heart attack. His death was followed by scenes of North Koreans wailing in the streets of Pyongyang, and of the 20-something son leading ranks of uniformed officials through funeral and mourning rites.
North Koreans across the country stood still at midday to honour the former ruler, as Kim Jong Un attended a ceremony to reopen the mausoleum where his father and his grandfather lie in state.