A virtual viewpoint image generation method for generating a virtual viewpoint image that is an image of an object viewed from a virtual viewpoint based on plural images of the object taken by plural cameras. Projection planes having a multi-layered structure are set on the images of the object, corresponding to a projection point of a projection plane. Color information of each projection point is determined based on color information of corresponding points, for each of the projection points overlapping when viewed from a reference viewpoint in a space. A degree of probability that the object exists at a distance corresponding to a position of the projection point is determined based on a degree of correlation of the corresponding points.