Abdellatif Merdas was gunned down late Tuesday near his home in the well-off southern district of Californie.
His assassins fled the scene.
The 53-year-old was in his official car when he was hit three times by shotgun fire, private news websites reported.
They showed photos of the scene and the car with broken windows.
Merdas was a member of the liberal Constitutional Union (UC) party, representing the Ben Ahmed district 60 kilometres south of Casablanca.
Shootings are rare in Morocco, where there are few illegal firearms.
Today morning, the authorities had not commented on the incident.