The Microsoft-founder was in Norway on Friday to lobby Prime Minister Erna Solberg to maintain Norway's funding for projects run by his charitable foundation.
He said that pouring oil fund money into infrastructure in poor countries, even if it was done for profit, would nonetheless bring huge benefits to the countries invested in.
"The area where you may get this dual benefit is … in sub-Saharan Africa and some of the countries in Asia," Gates said.
"That's an asset class, which could absorb, if it was well managed, an additional $10 billion… I'm not talking about a gigantic amount."
"Norway is by many measures one of the richest countries in the world and you can afford to take some of that money and help out people in other places," he said after he arrived in Oslo.
Norway is presently reviewing the investment strategy of its fund, which is the biggest sovereign wealth fund in the world.
"It is part of our platform that the oil fund should invest more in developing markets," Solberg said after her meeting.
"We will make sure the fund gets a mandate that allows them to invest in companies and maybe also infrastructure in these developing countries. We believe it can give just as good a return as similar investments in developed nations."
Norway's fund already owns about 1.25 percent of all global equities. If it was shared out equally between the country's 5.1 million citizens, it would make everyone in the country a
a krone millionaire.