Proposed are an apparatus and method for spinal surgery planning, the spinal surgery planning method including: acquiring a two-dimensional (2D) spinal image of a patient through a medical imaging apparatus; calculating a registration relationship between coordinates in an image space and coordinates in a surgical space by registering the image space for the spinal image and the surgical space where spinal surgery is performed on the patient; generating a virtual three-dimensional (3D) figure in the surgical space; projecting the 3D figure onto the spinal image based on the registration relationship; adjusting the 3D figure so that the 3D figure can correspond to a predetermined landmark on the spinal image; and setting an insertion position and insertion path of a spinal prosthesis based on the spinal image and the 3D figure.