  As a consequence of Wan's theorem about Dwork's conjecture, the unit root
$L$-functions of the $n$-dimensional Kloosterman family are $p$-adic
meromorphic. By studying the symmetric power $L$-functions associated to the
Kloosterman family, we prove that for each $0\le j\le n$, the unit root
$L$-function coming from slope $j$ has a unique unit root which equals 1.
