Abstract This paper presents a new conception-the brain function state diagram (BFSD) or brain fucntion state mapping (BFSM) which describes the function cases of brain and gives the method for finding BFSD or BFSM from the brain electrical wave (BEW). In this paper the brain function state diagrams of rabbits are normal and epileptic fit. The results indicate that BFSD which shows the informations on epileptic fit are sufficient, marked, immediate and simple.