1. A section reconstruction method for projecting radiographic data of an object acquired in each scan position back to a section reconstruction area, said method comprising the step of: generating enlarged interpolation data by interpolating back projection data and then projecting said enlarged interpolation data back to a two-dimensional or three-dimensional reconstruction area virtually set to a region of interest of said object, said back projection data being radiographic data, or data resulting from filtering of said radiographic data, said radiographic data being acquired in each scan position by causing a radiation source and a detector arranged opposite each other across said object to scan said object synchronously, or to scan said object synchronously with rotation of said object, said radiation source irradiating said object with electromagnetic waves capable of penetrating said object, said detector detecting electromagnetic waves transmitted through said object.