The present invention provides a form measuring device including a measuring section (302) for obtaining measurement data obtained by measuring a space between a straightedge rule (321) and an edge of an object to be measured (305) paired with each other, a function value setting section for setting form-function values, which indicates distances from a reference line R to the straightedge rule (321) and to edges of the object to be measured, and angle-function values .theta., which indicates internal angles of the object to be measured 305 and an angle formed by the straightedge rules (321), a simultaneous equation deriving section for deriving simultaneous equations for pains each consisting of the straightedge rule (321) and an edge of the object to be measured (305) based on the measurement data, and a simultaneous equation processing section for processing the derived simultaneous equations.