PageHeader : Funkcialaj Ekvacioj, 45 (2002) 373-386 Title : The $L^{2_{-}}$ boundedness of Pseudodifferential Operators with Simple Title : Symbols AuthorInfo : By AuthorInfo : Yoichi MIYAZAKI* AuthorInfo : (Nihon University, Japan) section : 1. Introduction section : 2. Statement of the main theorem section : 3. Smoothness of the symbol section : 4. Estimates of integral kernels section : 5. Proof of the main theorem section : References