The spectra of the Toeplitz operators on the weighted Hardy space ${{H}^{2}}\,(W\,d\theta \,/\,2\pi )$ and the Hardy space ${{H}^{p}}\,(d\theta \,/\,2\pi )$, and the singular integral operators on the Lebesgue space ${{L}^{2}}\,(d\theta \,/\,2\pi )$ are studied. For example, the theorems of Brown-Halmos type and Hartman-Wintner type are studied.