This paper reports a novel immunoassay using an electro-microchip to detect the immuno-reaction signal, a gold nanoparticles (AuNPs) as a label of antigen or antibody and as a catalyst for silver precipitation, and the silver enhancement reaction to magnify the detection signal. The LCR meter instrument, a new detection method for immunoassay, is used to detect the electric single in a sandwich format. The change of the resistance to corroborate immuno-reaction is detected, amplified and analyzed to construct this new immunoassay. Different sizes of the electrodes are designed to discuss the relationship between gap size and sensitivity. In addition, the specificity, sensitivity and the detection limit of the electro-immunoassay are discussed. Using electro-microchip, nanoparticle and silver enhancement provided a new immunoassay method.