An ion optical apparatus and a mass spectrometer are provided. The ion optical apparatus includes at least one planar insulating substrate which is covered with metal patterns to form an electrode array including a plurality of cell electrodes, wherein each of the cell electrodes is arrayed according to a first direction to form a geometric pattern distribution of the electrode array, wherein cell electrodes are applied with radio frequency (RF) voltages having different phases to confine ions, a direct current (DC) voltage gradient is applied along at least part of the cell electrodes in the electrode array to drive ions to move in the first direction along the electrode array, and a corresponding electric field distribution is formed by the geometric pattern distribution to drive ions to move in a second direction substantially orthogonal to the first direction, thereby realizing ion deflection, focusing or defocusing.