An automobile lower body structure includes a floor panel having a tunnel structure extending longitudinally of a vehicle body at a location substantially centrally thereof, a dashboard lower panel secured to the front end of the floor panel, and a dashboard lower cross member extending transversely of the vehicle body and secured to the lower surface of the dashboard lower panel. The dashboard lower cross member has opposite ends secured to respective of two front side frames extending longitudinally of the vehicle body at opposite sides thereof, and a rearwardly extending intermediate portion partitioning the inside of the tunnel structure so that a closed cross section is formed at an upper portion within the tunnel structure.