The bomber struck the convoy of Gen. Sayed Ahmad Sadat at 8:30 a.m. as he was driving by on his way to work in Maimanah, capital of Faryab province, the local deputy governor Abdul Satar Barez said.
Barez said a bystander, a young boy roughly 3 years old, was killed while Sadat and four of his bodyguards were wounded.
Faryab is in a relatively peaceful area of Afghanistan, where a U.S.-led coalition is battling the Taliban and affiliated insurgents.
Insurgents have been waging a campaign of assassinations against Afghan officials and others aligned with the government and the U.S.-led coalition.