A hydraulic pressure reservoir having at least one pressure chamber formed between two opposed, movable inner boundary members. Each inner boundary members includes a spring cover and a diaphragm spring. An outer boundary member peripherally surrounds the movable inner boundary members and has a U-shaped cross section along at least a part of its periphery to axially support the diaphragm springs in a fixed axial position. The outer boundary member can be formed in several pieces that are held together by interconnections or by a surrounding outer tensioning member.