PURPOSE: To prevent generation of cracks near a radiator core side by joining the lower end of a radiator core side to the lower end portion of the radiator core lower, integrally forming extension portions extended backward, and fitting the extension portions to a mount bracket.

CONSTITUTION: A radiator core lower 20 having a hat-like section has an upper end portion 20a bent upward, which is joined to the front side of a radiator core side 22. Extension portions 23 are formed backward on both end portions of the lower end portion 20b, which corresponds to the radiator core side 22. A reinforcement 24 is connected to the upper surface of each extension portion 23 in an overlapping state, and the lower end portion 22a of the radiator core side 22 is fitted thereon. On the other hand, a body 21 is fixed, with the extension portion 23 put on a mount bracket 8 fixed to a front side member 6 through an insulator 9, by a fitting bolt 26.