1. A semiconductor device, comprising; a first neuron MOS transistor having a first semiconductor region of one conductivity type disposed on a substrate, a first source region and a first drain region of a conductivity type opposite to said first semiconductor region provided within said first semiconductor region, a first floating gate electrode having a floating potential and isolated from said first source region and said first drain region, said first floating gate electrode capacitively coupled to said first semiconductor region by means of a first insulation film, a plurality of control gate electrodes capacitively coupled to said first floating gate electrode by means of a second insulation film; a means for inputting a first signal into said first neuron MOS transistor connected to a first control gate electrode; and a first inverter comprising at least one stage and having an input and an output, said input connected to said means for inputting a first signal and said output connected to a second control gate electrode.