To provide a tamperproof pouring tool which enables the clear recognition that the cap is opened when a cap is once opened, even though the cap is mounted again on a container, and facilitates classified discarding.

A pouring tool main body (20) is at least equipped with a cylindrical body with a screw having a male screw (22) on the outer periphery of a cylindrical part (21), and the lower edge of the cylindrical body is extended outward to form an annular plate (23). A structure is constituted so that when the cap (10) is screwed on the cylindrical part, a projection (24) is formed on a periphery on which the end edge of a skirt part of the cap is overlapped, and an outer peripheral wall (25) is stood from the outer edge of the annular plate. The cap consists of a cap main body (11) with a male screw (12) on the inner periphery and a tamperproof ring (14) connected to its skirt part lower face through a bridging part (13). The ring consists of ring pieces (14a) divided into a plurality of the pieces with the bridging parts, and lower ratchet parts (141) and upper ratchet parts (142) are formed on the lower faces and the upper faces of respective ring pieces. The tamperproof ring (14) is held between the cylindrical part (21) and the outer peripheral wall (25).