  Let $H_0$ be a periodic operator on $\R^+$(or periodic Jacobi operator on
$\N$). It is known that the absolutely continuous spectrum of $H_0$ is
consisted of spectral bands $\cup[\alpha_l,\beta_l]$. Under the assumption that
$\limsup_{x\to \infty} x|V(x)|<\infty$ ($\limsup_{n\to \infty}
n|V(n)|<\infty$), the asymptotical behaviour of embedded eigenvalues
approaching to the spectral boundary is established.
