  The purpose of this paper is to prove pointwise inequalities and to establish
the boundedness on weighted $L^{p}$ spaces for pseudo-differential operators
$T_{a}$ defined by the symbol $a\in S^{m}_{\varrho,\delta}$ with
$0\leq\varrho\leq1,$ $0\leq\delta<1$.
  Firstly, we prove that if $m\leq-n(1-\varrho)/2$, then
$$(T_{a}u)^{\sharp}(x)\lesssim M(|u|^{2})^{1/2}(x)$$ for all
$x\in\mathbb{R}^{n}$ and all Schwartz function $u$. Secondly, it is shown that
if $1\leq r\leq2$ and $m\leq-\frac{n}{r}(1-\varrho)$, then for any $\omega$
belongs to the class of Muckenhoupt weights $A_{p/r}$ with $r<p<\infty$, these
operators are bounded on $L^{p}_\omega$. Moreover, these results are sharp on
the bound of $m$.
