The IRB has come under-fire for its decision with many believing awarding the tournament to Japan would have done much to boost the game in what is seen as an emerging region for the sport.
New Zealand won the secret ballot, held in Dublin, last week.
But the IRB has hit back at criticism, saying it was committed to growing the game globally.
A statement said: “Since the announcement of the host union for Rugby World Cup 2011 there has been a lot said and written about the future growth and development of rugby worldwide.
“The IRB would like to make it very clear that there is in place a fully funded strategic plan for the development of the game. In August the IRB announced an unprecedented three-year £30 million strategic investment programme. This was a clear commitment to developing rugby globally and increasing competitiveness.
“The Rugby World Cup, our premier event, takes place once every four years. And while the placement of the tournament does play a role in the development of rugby, it is what happens during the rest of the four-year cycle and beyond that really grows the game.
“The IRB is totally committed to making rugby a truly global sport.”
