To prevent a bursting sound generated when a mixed and kneaded material obtained by mixing and kneading predetermined amounts of a powder component and a liquid component in a capsule for a tooth restorative material is administrated to a position to be restored in a patient's tooth, the capsule is structured such that a protrusion portion (4c) having its inner end positioned slightly inside an outer periphery of a circular hole of a first opening forming portion (1b) is provided on a rear end portion of a nozzle (4) in such a manner as to be positioned at a position which is in the vicinity of the first opening forming portion (1b) to form the circular hole for an outlet of a mixed and kneaded material (C) of a powder component storing cup (1) and is away from at least a hinge portion of the circular hole.