A sputter ion pump with the pumping cells assembled in an annular configuration is developed. The pump is characterized by following factors; 1) minimized residual magnetic field intensity at the center of annular configuration about 80 A/m, 2) high effective pumping speed larger than 0.03 m³/s and 3) low ultimate pressure about 4 × 10^-9 Pa. The design is suited for pumping the electron beam equipment such as scanning electron microscope, etc.