The landmine detonated on the road leading to the American base at the Baghdad International Airport, according to the US commander in Iraq.
His was the third death the occupiers have suffered in the last 24 hours in Iraq.
Earlier, US headquarters near the town of Ba'aquba, about 60 km from Baghdad, came under rocket-propelled grenade (RPG) attack leaving one soldier dead, eyewitnesses told our correspondent.
The report could not be independently verified.
Overnight a US soldier was also killed and two others wounded 40 km northeast of Ba'aquba.
In a separate attack on Thursday, a rocket-propelled grenade (RPG) was fired in central Baghdad at a US tank but did not hit its target.
In the northern Iraqi city of Mosul, RPGs were fired at a US armoured vehicle in the early hours of Thursday. It was not clear whether there were any casualties.
US troops cordoned off the area, next to the city's university, and deployed soldiers in nearby streets.
At least 52 US soldiers have been killed in resistance attacks since 1 May when US President George W Bush declared an end to hostilities.
Since then, resistance attacks have gained steam and spread throughout the country into areas such as the mainly Shi’I south and Kurdish north which Washington had perceived as allies.