To provide a ventilating device for a helmet excellent in assembling operation efficiency and capable of preventing a gap from forming between a member and a shell.

This ventilating device for a helmet is obtained by forming through-holes 53 and 53A in a shell 2, providing communicating cylinders 51 and 57A in an opening and closing member 54, inserting the communicating cylinders 57 and 57A into the through-holes 53 and 53A, bending the tips 57S of the communicating cylinders 57 and 57A to the inner surface side of the shell 2 and fixing the tips 57S by thermal welding. Thereby, the positional shift of the opening and closing member 54 in the direction of the outer surface of the shell 2 is prevented by the communicating cylinders 57 and 57A inserted into the through-holes 53 and 53A in the mounted state. Furthermore, the floating to the outside can always be prevented by fixed parts 60.