The IRB begin the tender process this month when they will invite all member unions to express their interest in staging the competition.
Unions will be able to submit a bid to host either the 2015 or 2019 tournament, or just one of the two.
IRB chairman Bernard Lapasset said: "We believe that awarding two tournaments together will provide a better time-frame for planning.
"It will also provide longer term certainty for hosts and commercial partners."
Every previous World Cup has been awarded to a major nation but Lapasset has indicated that the Rugby World Cup board are ready to broaden the sport's horizons.
New Zealand secured the rights for 2011, beating the populist choice of Japan who won many neutrals over with an accomplished bid only to lose the vote 13-8.
Japan were angered by what they viewed as a carve-up among the sport's major nations, with the decision to retain secret voting causing further dismay over the process.
But the emerging nation may consider producing a fresh bid in light of Lapasset's comments, while the likes of Argentina and Canada may also be interested.
Lapasset said: "As the revenue generation is vital to our ongoing development plans we recognise that the World Cup has to be held in one of our senior core markets on a regular basis.
"However, the commercial success of the tournament also means we can now consider placing the tournament in new developing markets to assist the game's strategic growth."
Lapasset hailed last year's World Cup in France as a major success that will help expand the sport.
He said: "The 2007 tournament enjoyed a cumulative global TV audience of four billion while 2.2 million fans attended matches.
"It is vital we continue to maximise the popularity and success of the tournament.
"It is the major building block of the game as it provides substantial investment revenue for the development of rugby around the world.
"Last year's tournament generated a surplus of over £120million which has been reinvested through grants to unions, the underwriting of international tournaments and the funding of targeted strategic high performance programmes."