The present invention provides an electrolytic processing apparatus and an electrolytic processing method which can perform processing of a substrate without destroying devices formed in the substrate even when a fragile material is employed in the substrate and which can reduce non-uniformity in the contact pressure of an electrode member on a substrate during processing, thereby equalizing the processing amount in the entire processing surface of the substrate and the surface roughness after processing. The electrolytic processing apparatus includes: a substrate holder for holding a substrate; an electrode base provided with an electrode member for contact with the substrate, held by the substrate holder, in the presence of a liquid to effect processing of the substrate; and a support base for floatingly supporting the electrode base by a floating mechanism.