Geir Lundestad, ex-secretary of the Nobel committee, told AP news agency that the committee hoped the award would strengthen outgoing President Obama’s resolve to achieve peace.
Critisizms arose as it was not understood what he had done to deserve the prize.
Mr Lundestad, writing in his memoir, Secretary of Peace, said even Obama had been surprised.
“No Nobel Peace Prize ever elicited more attention than the 2009 prize to Barack Obama,” Mr Lundestad wrote.
“Even many of Obama’s supporters believed that the prize was a mistake,” he says. “In that sense the committee didn’t achieve what it had hoped for”.
He also revealed how Obama considered not going to Norway’scapital, Oslo, to receive his prize.
“In the White House they quickly realised that they needed to travel to Oslo,” Mr Lundestad wrote.