A radiator fastener which tightens a radiator to a car body includes a first engagement member having a fit protrusion piece and fixed to the car body, and a second engagement member with a fit depressed portion, which is free to be fitted to and removed from the fit protrusion piece of the first engagement member. The second engagement member is engaged with a part of the radiator through an elastic member, and is fixed to the first engagement member. The radiator fastener can be tightened through one-touch operation and this improves workability significantly.