  Let $\mathcal{E}_n$ be the ring of the germs of
$\mathcal{C}^\infty$-functions at the origin in $\R^n$. It is well known that
if $I$ is an ideal of $\mathcal{E}_n$, generated by a finite number of germs of
analytic functions, then $I$ is closed. In this paper we consider an ideal of
$\mathcal{E}_n$ generated by a finite number of germs in some class of
$\mathcal{C}^\infty$-functions that are not analytic in $\`a$, but
quasi-analytic and we shall prove that the result holds in this general
situation. We remark that the result is not true for a general ideal of finite
type of $\mathcal{E}_n$.
