The present invention discloses an improved operating fluid reservoir (1) having a venting and/or air admission valve. The operating fluid reservoir (1) is characterized in that a valve housing (10) is formed integrally with an operating fluid reservoir wall (2). A vent opening (3), via which a valve housing interior (11) is in fluid communication with a vent line (5), is embodied as a through opening (3) through the operating fluid reservoir wall (2). A valve body (20), which is arranged in the valve housing interior (11), can be introduced into the valve housing interior (11) via an introduction opening (16) in the valve housing (10). The valve body (20) comprises a holding device (23; 14, 24), by means of which the valve body (20) is held movably in the valve housing (10).