Firefighters and volunteers have been sifting through the rubble since early Friday after two floors of the four-storey block in the town of Torre Annunziata, at the foot of the volcano Mount Vesuvius, collapsed at around 6:30 am (0430 GMT).
The last body was found early on Saturday after teams searched through the night.
Local media reports said the victims included the municipal architect in charge of security checks for public and private buildings in the area of some 40,000 inhabitants at the foot of Mount Vesuvius.
His wife and 27-year-old son were also killed in the collapse, which occurred in the part of the building where bedrooms were located.
A couple with two children, aged 8 and 14, were also killed, along with a 65-year-old woman who lived alone.
Some 30 firefighters, joined by dozens of volunteers and relatives of the missing using their bare hands, searched the wreckage for survivors.
The fire service said three officers had been lightly injured during search operations.
"It is clear that this building was in bad shape," local mayor Vincenzo Ascione said. "I regret that no city technician had been able to recognise the situation because there had to have been a sign".
Witnesses said a freight train passed on the neighbouring railway track just before the building collapsed, while others noted that renovation works had been under way on the lower floors.
The prosecutors' office in Torre Annunziata has opened an inquiry over suspected negligence, but no cause for the collapse has yet been determined.