The extraction of Cu(II) as a model was examined based on tube radial distribution of a ternary mixed carrier solution of water-acetonitrile-ethyl acetate (2:3:1 volume ratio) in a microchannel in a microchip. A microchip incorporating microchannels in which one wide channel was separated into three narrow channels was designed and manufactured. When the ternary carrier solution was fed into the wide channel under laminar flow conditions, the carrier solvent molecules were radially distributed in the channel, generating inner (organic solvent-rich major) and outer (water-rich minor) phases. The Cu(II) dissolved in the carrier solution was distributed between the inner and outer phases due to its hydrophilic nature and then collected through the three narrow channels. The concentrations of Cu(II) in the two side narrow channels were greater than that in the center narrow channel through extraction.