A plug-type sealing assembly for hermetically closing a filler hole 24 of a lid 19 of a container 20, comprises: a plug 1 having a rod portion 3 in an upper part of which a large-diameter head portion 2 is formed, the rod portion 3 having a male screw 5 in its outer peripheral surface; and, a sleeve 8 provided with an axial through-hole together with a countersunk head portion 10 and a slit skirt portion 11 extending downward from a lower end of said countersunk head portion 10. In the through-hole, a female screw 15a, 15b is formed. In the container 20: through the filler hole 24 a sealant 23 is supplied between joint portions of the container 20 so that the container 20 is hermetically sealed; and, the sealing assembly is easily removed from the filler hole 24 to ensure that the sealant 23 is supplemented or replaced with a new one through the filler hole 24 in an easy and a safety manner, and easily mounted again in the filler hole 24 after completion of such supplementing or replacing operation of the sealant 23, by threadably engaging the male screw 5 of the plug 1 with and disengaging from the female screw 15a, 15b of the sleeve 8.