The sources initially said a car bomber had rammed into the convoy of Hisham Barakat. Later, they said the car bomb apparently was detonated remotely. Two civilians and two policemen were also wounded.
Judges and other officials have increasingly been targeted by militants opposed to President Abdel Fattah el-Sisi and apparently angered by hefty prison sentences imposed on members of the now-outlawed Muslim Brotherhood.
A little-known group calling itself the "Giza Popular Resistance" claimed responsibility on its Facebook page for the attack. Reuters could not verify the claim.
Last month, ISIL's Egypt affiliate urged followers to attack judges, opening a new front in the insurgency in the world's most populous Arab state. The same month, three judges were shot dead in the northern Sinai city of al-Arish.
Assistant public prosecutor Zakariya Abdel Aziz said the attack was an assassination attempt against Barakat. The bomb exploded as he left his home in the neighborhood of Heliopolis for his office.
Health ministry spokesman Hossam Abdel Ghaffar said Barakat had suffered a dislocated shoulder and a deep cut and may have fractured his nose. He was in stable condition and was currently in a recovery room after surgery, Abdel Ghaffar said.
Eyewitnesses said the explosion was strong enough to shatter glass in nearby storefronts and homes. A large plume of black smoke and several smoldering cars were seen near apartment buildings.
Barakat's place of work was also targeted earlier this year when a bomb exploded near the High Court in central Cairo, killing two people.
Egypt is facing a Sinai-based insurgency that has killed hundreds of policemen and soldiers since the army toppled President Mohamed Mursi after mass protests against his rule in 2013.