In this study, we provide a simple, low-cost, and novel method of constructing microelectrodes on both sides of a fluid microchannel to be utilized as an electroosmotic micromixer. The electrodes mounted on both sides of the microchannel provide unique characteristics for biological studies, electrokinetics, dielectrophoresis, and so forth. The fabrication process includes optical lithography, layer deposition to create electrodes, accurate alignment, and bonding of two wafers. Compared with other methods used for fabricating electrodes on both sides of microchannels, the method proposed in this study does not require very difficult and complex experimental conditions, cumbersome processes and expensive equipment. The distribution of the electric field is numerically analyzed for two electrode arrangements. The numerical analysis shows that the efficiency of the electrodes mounted on both sides of the microchannel is higher than that of the electrodes mounted on one side. The proposed technique is a good alternative to the one-side electrodes and other double-side electrode configurations for electroosmotic micromixers. The process simplicity provides an easy way of constructing microelectrodes on both sides of the microchannel for mixing fluids.