Provided is a roll unit for use in a surface treatment of a copper foil, wherein shaft sleeves are fitted to a roll shaft of a roll so that the roll shaft is rotatably supported by a bearing via the shaft sleeves. Additionally provided is a roll unit wherein the shaft sleeves consist of two sleeves, namely a roll-side sleeve arranged on a roll main body side and a tapered sleeve arranged on a shaft end side, an oil seal is arranged between the roll-side sleeve and a bearing box, and the tapered sleeve is supported by a bearing disposed in the bearing box. Thus, this invention relates to a roll unit to be used in electrochemical surface treatments, such as roughening treatment, rust prevention treatment and surface oxidation treatment, to be continuously performed on a surface of a rolled copper foil or an electrolytic copper foil, and in particular relates to a roll unit capable of inhibiting the abrasion and corrosion of the roll shaft of such roll unit and capable of simple replacement of the bearing box, bearing and other components.