"Unfortunately, within the borders of Angola, there are still many poor people demanding that their rights be respected," the pope said upon arriving.
"The multitude of Angolans who live below the threshold of absolute poverty must not be forgotten. Do not disappoint their expectations."
"Do not yield to the law of the strongest," he added.
Later, in a nationally televised speech from Angola's presidential palace, he called on Africa to show "a determination born from the conversion of hearts to excise corruption once and for all."
"Armed with integrity, magnanimity and compassion, you can transform this continent, freeing your people from the scourges of greed, violence and unrest," he said.
He also called for "respect and promotion of human rights, transparent governance, an independent judiciary, a free press, a civil service of integrity, a properly functioning network of schools and hospitals."
Many of those are still lacking in Angola, where President Eduardo dos Santos has ruled for 30 years, and where a bloody civil war ended only in 2002.
Since then, Angola's economy has boomed thanks to oil exports, but the government remains restrictive and was ranked by Transparency International as among the most corrupt in the world.
The Catholic church is one of the few strong, national voices outside of Angola's government, and church leaders here have expresed hope that Benedict would pressure Dos Santos to allow a Catholic radio station -- one of the few independent media -- to broadcast nationally.
During his speech, Benedict took aim at a part of the African Union's charter that guarantees women a right to an abortion in cases of rape, incest, or major health risks to the mother, saying abortion was not a health issue.
"How bitter the irony of those who promote abortion as a form of 'maternal' healthcare," he said. "How disconcerting the claim that the termination of life is a matter of reproductive health."
The comments followed controversial remarks made en route to Cameroon on Tuesday, when he said that AIDS "cannot be overcome through the distribution of condoms, which even aggravates the problems."
The comments sparked an uproar among AIDS activists as well as some governments, who warned that the pope's remarks could harm prevention campaigns.
But the controversy hasn't dampened the enthusiasm for the pope's visit in Angola, where the population is 55 percent Catholic.
Thousands of people began gathering at the airport from dawn to see him, carrying banners saying "Welcome Pope Benedict" and "Bless our country". Many ran alongside his motorcade as it rolled towards the city.
"I was one of the first to get here at 6:00 am because I wanted to get a good place so I can see Pope Benedict when he drives past," Adriana Juliao, 24, told AFP. "It means so much to us that the pope is coming here to Angola."
Sister Isabel Benjamin, a 43-year-old missionary, said she hoped Benedict's visit would help cement Angola's peace.
"Before Angola was a war country and now we're experiencing peace and the Pope coming here is really a very exciting moment for us... and I hope by the pope coming he will bring us a lasting peace."