The man, who has been detained at Rome's Regina Coeli prison, was diagnosed with HIV in 2006, Corriere reported.
He faces charges of “grievous and incurable bodily harm” against the six women, who he had sex with between 2006 and 2009, and will remain in custody while police ascertain if others have been infected with the virus.
The man, called Valentino, allegedly asked the women to forgo using a condom during sexual intercourse despite knowing he was HIV positive, prosecutors said.
“I did not intend to cause them harm, it was an error of judgement,” he told Corriere from prison.
Valentino, who currently has a partner of the same age, is alleged to have met some of the women through social networks such as Facebook and WhatsApp, occasionally proposing threesomes.
“The women were there, some responded straightaway...I didn't force anyone, they were up for it too,” he said, adding that it was akin to a game of Russian roulette.
“Sometimes it goes wrong, but most often not. I lived with some of these women – we were in love, we had breakfast together in the morning, why should I have hurt them?”
His lawyer, Giuseppe Minutolo, argued that his HIV infection was “regressive” enough to “make infection unlikely”.
“This is why my client has felt able to manage the disease and reduce the impact on his partners.”
Minutolo pointed to the fact that his current girlfriend tested negative for HIV.
“It's proof that my client is not a monster,” he said of Valentino, whose parents died when he was eight, after which he was mostly raised by an uncle.
“He is a guy who lacked emotional education, but nothing more than that.”
The arrest came on the same week the world marked World Aids Day and also coincided with the publication of a report which said that that 3,695 people in Italy were diagnosed with HIV in 2014, a number which has seen little change over the past three years.
Most of the new diagnoses were among 25 to 29-year-olds, who mostly became infected after not using a condom during sex, the report from Italy's higher institute of health (ISS) said. Forty percent of those diagnosed with HIV last year were homosexual men.