We have investigated the mixing property of two liquids in micro channels where at least one of the liquids has viscoelasticity. As the first stage of this study, we have examined two types of T-shaped channels of millimeter order, i.e. a smooth channel and a channel with blocks at the mixing region. Colored water and sodium polyacrylate aqueous solutions of 100ppm and 1000ppm were tested and saturation of the dye diffused was measured. In the smooth T-shaped channel, polymer solutions with high viscosity were difficult to mix with water. However, in the T-shaped channel with blocks, high mixing efficiency was obtained even at low flow rates by utilizing polymer solutions. It is considered that Barus effect generated after the blocks with elastic properties of the polymer solutions improved the mixing in the flow.