To enable quick and reliable execution of an operation of applying stamp ink on the surface of a printing die sheet in accordance with the area to be coated with the ink.

In the case when a second fitting part 56 of a releasing body 54 is fitted on a head part 52 having a discharge hole 53 in a flexible vessel 51 holding stamp ink 50, the shape of a flexible valve element 60 is changed by a pressure generated when the stamp ink 50 is forced out, and thereby communication passages 58 in the direction of a large-bore releasing part 57 can be closed up, while communication is so made that the stamp ink flows to a small-bore releasing part 61 on the first fitting part 55 side. Thereby the ink can be applied in a relatively small sectional area. At the time when a first fitting part 55 is fitted on the head part 52, to the contrary, the stamp ink 50 can be released from the large-bore releasing part 57 through the communication passages 58 and from the second fitting part 56 in the inside-diameter part of the part 57 and thus a large coating area can be coated with the ink by one application thereof.