PURPOSE: To absorb the load due to collision effectively with the front of a car body by branching the front of a side frame up and down.

CONSTITUTION: The rear end of a side frame 12 is connected to the under frame 16 formed in a closed cross section shape below a cabin floor 14. The front section of the side frame 12 is branched into a lower branch end 20 and upper branch end 22, then a front cross member 18 with an engine fitting member 30 is fitted to the lower branch end 20, and a bumper fitting hole 52 is provided on the upper branch end 22. The closed cross section of the upper branch end 22 is formed smaller as compared with that of the lower branch end 20. Since the cross member 18 for fitting an engine mount is fitted to the lower branch end 20, the engine drops under the car body when the load due to collision is large, thus the retreat of a dash lower panel rarely occurs.