The evening blast in the predominantly Sunni Arab city of Samarra also wounded at least 26 people, a police officer and a doctor said. Among the dead were women and children.
The bomb went off in the middle of the market at 6:45 pm (1545 GMT), when poorer Iraqis typically frequent it in order to take advantage of reduced prices as stalls look to get rid of surplus stock before closing for the night.
The violence comes a day after at least 75 people were killed and more than 200 wounded in a wave of shootings and bombings across Iraq, including a spate of bombings in Baghdad.
