"We're going to need to work a little more and a little later in life if we're going to meet our welfare ambitions," Reinfeldt told the TT news agency.
Reinfeldt's comments came as the government Commission on the Future (Framtidskommissionen) issued its report on an aging population and the workforce.
Simply raising taxes won't be enough to sustain expenditures associated with Sweden's welfare state, the report finds, arguing instead for raising the retirement age in line with increases in life expectancy.
Reinfeldt refused to offer any specifics on how much later in life Swedes should expect to work, explaining the decision will be up to the individual.
"It's not going to be the same answer for everyone as everyone's situation is different," he said.
The prime minister emphasized that he's in favour of using incentives such as tax breaks to help entice people to continue working.
The report also found that employers are going to have to adjust to the needs of older workers and that Swedes can expect to need to change careers in order to work longer
In addition, young Swedes need to finish their studies and enter the labour market sooner.
"We can have a continued positive development our welfare standards, but it can't stay on autopilot," the report said.
"Doing nothing at all is a strategy that risks bringing about major and uncontrolled economic imbalances between generations and regions."