We propose an optical scanning holography (OSH) for optical reconstruction with equal scale magnification or demagnification ratio along the transverse and longitudinal directions when the magnification or demagnification ratio of the hologram is priori known. First, we review the principles of OSH. Second, we propose an equal scale OSH that encodes a 3D distribution of a 3D scene with a scanning beam pattern that is formed by the superposition of two spherical waves with the same curvature direction. The hologram recorded by the equal scale OSH reconstructs the 3D scene with equal scale magnification or demagnification along the transverse and longitudinal directions. Finally, we provide simulation and experiment results to illustrate and clarify the proposed idea.