1. A chaos theoretical brain function diagnosis apparatus for diagnosing a brain function of a subject by giving a load to a functional site of a living organism of the subject, receiving a reaction emitted from the living organism of the subject as an electric signal, and analyzing the electric signal, wherein the apparatus is characterized by functions of selecting at least two from among a voice signal, an nystagmus signal, a pulse wave signal and a gravity center swinging signal as the electric signal; calculating chaos theoretical indexes such as Lyapunov exponents according to a chaos theoretical technique; detecting changes in the chaos theoretical indexes with passage of time; and collectively evaluating and diagnosing the brain function.