In a system having an interface which utilizes electroencephalogram, it is determined whether the user was looking at a menu or not based on the frequency of the user electroencephalogram, and the electroencephalogram is excluded from the subject of distinction in the case where the user is not looking at the menu.A distinction necessity determination apparatus 10 for determining whether or not to perform a distinction of an electroencephalogram signal in an electroencephalogram interface system 1 includes a frequency analysis section 11 for calculating a representative frequency at which frequency power of the electroencephalogram signal becomes maximal, and a determination section 12. Based on a relative quantity between the switching frequency of menu items and the representative frequency of the electroencephalogram signal, the determination section 12 determines whether the representative frequency is related to switching of the menu items or not, and based on the result of determination, outputs to an electroencephalogram interface section 100 an instruction to adjust the distinction method for the electroencephalogram signal to be adopted in the electroencephalogram interface section 100.
