In a compressor having a discharge valve mechanism, a valve retainer has a curved surface which is faced to and spaced from a movable portion of a flexible plate-like discharge valve and adapted to limit the movement of the movable portion. In a first direction parallel to the valve plate, the movable portion extends from a fixed portion, fixed to a valve plate, to face an exit end of a discharge hole of the valve plate. The curved surface has a plurality of parts different in radius of curvature from one another in a second direction parallel to the valve plate and perpendicular to the first direction.