"Four civilians were martyred and another 14 were wounded," provincial governor's spokesman Faizanullah Pattan told Agence France Presse, adding that he did not know what the attacker's target had been.
There were no government offices or military patrols in the area where the incident happened in the small town of Najeel Khail in Alishing district of Laghman province, about 100 kilometers east of the capital Kabul.
The explosives were strapped to the bomber's body, the spokesman said.
A wave of Taliban suicide bombings has accompanied the militants' announcement of the start of their annual spring offensive late last month.
On Sunday, six members of the Afghan security forces were killed when the Taliban stormed a traffic police office and two suicide bombers detonated their explosives in a nine-hour standoff.
On Saturday, six medical students were killed by a suicide bomber who struck as they ate lunch in a tent at Kabul's heavily-guarded military hospital.
Civilians are often victims of the fighting in Afghanistan, which has run for nearly 10 years as 130,000 foreign troops try to put down a Taliban insurgency sparked by the 2001 U.S.-led invasion to oust their Islamist regime.
Last year was the deadliest for civilians since the conflict began, according to the United Nations, with 2,777 killed -- a 15 percent increase on 2009.
Elsewhere in Afghanistan Monday, the interior ministry said seven insurgents were killed after Afghan and foreign forces repelled an attempted ambush in the highly unstable eastern province of Kunar, which borders Pakistan.
Of the 130,000 international troops currently in Afghanistan, the bulk of them are from the United States.
Afghan security forces are due to take over responsibility for security in a handful of safer areas from July, allowing some foreign troop withdrawals.
All international combat troops are due to be pulled out by 2014 although there have been calls for this timetable to be speeded up since the killing of al-Qaida leader Osama bin Laden by U.S. forces in Pakistan on May 2.(AFP)