1. A form recognition apparatus for recognizing a character string existing in an arbitrary table structure in a form, comprising: an image acquisition unit capable of obtaining a digitized form image of the form; a character string recognition unit capable of recognizing a character string existing in the form image obtained by the image acquisition unit; a character string extraction unit capable of extracting a headline wording consisting of a predetermined character string from character strings recognized by the character string recognition unit; a table structure determination unit capable of determining a table structure existing in the form image, on the basis of each of the headline wordings extracted by the character string extraction unit entirely from the form image and arrangement of each of the headline wordings in the form image, when the character string extraction unit extracted plurality of the headline wording; a correspondence relationship specification unit capable of specifying a correspondence relationship between the headline wording and a character string other than the headline wording recognized by the character string recognition unit, using a determination result of the table structure by the table structure determination unit; and a storage unit capable of storing a database in which headline wordings that may appear in a unit table structure being a unit for entering one or more pieces of related data in the form are defined in a hierarchical structure for each unit table structure, wherein the table structure determination unit determines the entire table structure existing in the form image, referring to the database stored in the storage unit.