Several characteristics of a charged mosaic membrane with parallel array of negative and positive charges were investigated by using transport studies and the related analysis. From an analysis of the volume flux and salt flux based on irreversible thermodynamics, preferential salt transport across the charged mosaic membrane was clearly demonstrated. Additionally, transport properties of amino acids and sucrose through the charged mosaic membrane were estimated, relatively, on the basis of KCl transport. As a result, amino acid transport depends largely on the charged states and molecular weight; however, for sucrose transport, non-electrolyte was rejected under all experimental conditions.