A vehicle body includes hollow left and right side sills. Front ends of the side sills are formed into closed cross sections and substantially inverted-L shapes. The front end of the right side sill is bilaterally symmetrical to the front end of the left side sill. Rear ends of the left and right side sills are formed into substantially square-shaped cross sections. Portions from the front ends to the rear ends of the side sills are formed into closed cross sections which change smoothly from the inverted-L shaped cross sections to the square-shaped cross sections.