To provide a drain device for a radiator capable of preventing high temperature cooling water from splashing on the hand of a worker who rotates and operates a cock part of a drain plug.

The drain plug 8 screwed to a drain pipe 6 and opening/closing a delivery pipe 7 is provided with a cup-shaped cover 31 opened to the drain pipe 6 side between the cock part 22 and a rod-shaped plug 21. The drain device 3 is provided with a slip preventing means 34 for preventing the drain plug 8 from slipping out of the drain pipe 6. Therefore, even when the drain plug 8 is excessively turned to a loosening direction, the state that the rod-shaped plug 21 is inserted in the drain pipe 6 can be maintained by the slip preventing means 34, and an amount of the cooling water flowing from an end of the drain pipe 6 can be restrained small. The small amount of the cooling water is made to flow to the direction opposite from the hand of the worker by the cover 31, and a fault that the cooling water splashes on the hand of the worker operating the cock part 22 can be prevented.