To prevent a seal from tumbling down from a cover when it is put on the cover, by a constitution wherein a notched recess wherein the side part of the seal can be fitted or a pair of projections which can hold the seal between are provided in the edge of the circumferential wall of the cover.

Almost semicircular notched recesses 5 wherein the side part of a seal 38 can be fitted are provided in the edge of the circumferential wall 4 of a cover 3 which can be fitted on and removed from a case main body 2 filled with red seal-ink 1. In this case, the notched recesses 5 are not limited to two, but can be provided in desired numbers. Besides, the notched recesses 5 are not limited in the shape to almost semicircular notches, but can be provided also as a pair of projections which can hold the seal 38 between. According to this constitution the seal 38 can be prevented from tumbling down from the cover when it is put on the opened cover at a break of sealing, and it can be avoided that the red seal-ink on the face of the seal stains papers or a desk.