A shape data generation method, comprising: allocating brightness values of first voxels in a first voxel space to corresponding second voxels in a second voxel space, wherein the first voxel space contains a plurality of tomographic images of an object, the second voxel space contains a target shape of transformation, and each of the first voxels is located in any one of the plurality of tomographic images; first setting, to a predetermined brightness value, brightness values of points that are on the target shape and are located on a part which corresponds to a boundary of the object in any one of the plurality of tomographic images; allocating, to each voxel which is in the second voxel space and does not have a brightness value, a brightness value of a third voxel which is closest to the voxel; accepting an input of first source landmarks on a first shape that is a reference shape of the object and is to be transformed and an input of first target landmarks on the target shape; first transforming the first shape so as to put each of the first source landmarks on a corresponding first target landmark; second setting a shape after the first transforming to the first shape; first specifying, from among a plurality of vertices of the first shape, a plurality of second source landmarks, wherein each second source landmark of the plurality of second source landmarks are placed at points that internally divide the line segments representing the normal lines of the second source landmarks; second specifying, for each of the plurality of second source landmarks, a second target landmark by a vector calculated by multiplying a unit normal vector for the second source landmark by a predetermined coefficient and a certain value calculated by dividing a number of times that the first shape has been transformed by a predetermined number of times; second transforming the first shape so as to put each of the plurality of second source landmarks on a corresponding second target landmark; third setting a shape after the second transforming to the first shape; and executing, for the first shape to which the shape after the second transforming has been set, the first specifying, the second specifying, the second transforming and the third setting the predetermined number of times. allocating brightness values of first voxels in a first voxel space to corresponding second voxels in a second voxel space, wherein the first voxel space contains a plurality of tomographic images of an object, the second voxel space contains a target shape of transformation, and each of the first voxels is located in any one of the plurality of tomographic images; first setting, to a predetermined brightness value, brightness values of points that are on the target shape and are located on a part which corresponds to a boundary of the object in any one of the plurality of tomographic images; allocating, to each voxel which is in the second voxel space and does not have a brightness value, a brightness value of a third voxel which is closest to the voxel; accepting an input of first source landmarks on a first shape that is a reference shape of the object and is to be transformed and an input of first target landmarks on the target shape; first transforming the first shape so as to put each of the first source landmarks on a corresponding first target landmark; second setting a shape after the first transforming to the first shape; first specifying, from among a plurality of vertices of the first shape, a plurality of second source landmarks, wherein each second source landmark of the plurality of second source landmarks are placed at points that internally divide the line segments representing the normal lines of the second source landmarks; second specifying, for each of the plurality of second source landmarks, a second target landmark by a vector calculated by multiplying a unit normal vector for the second source landmark by a predetermined coefficient and a certain value calculated by dividing a number of times that the first shape has been transformed by a predetermined number of times; second transforming the first shape so as to put each of the plurality of second source landmarks on a corresponding second target landmark; third setting a shape after the second transforming to the first shape; and executing, for the first shape to which the shape after the second transforming has been set, the first specifying, the second specifying, the second transforming and the third setting the predetermined number of times.