Abstract: A joint member is provided that can be easily installed, without sacrificing an appearance, in a joint groove required to secure water-tightness between adjoining wall surface facing members of a building. A joint base member 6 is integrally and consecutively installed on a surface of a synthetic resin joiner 4 positioned and provided between wall surface facing members A. The joint base member 6 has right and left side plates 12, two soft sealing tongue flaps 14a and 14b which are protuberantly provided on the outer side surfaces of the side plates and the distal ends of which come in contact with end surfaces of the wall surface facing members, and numerous apertures 16 drilled between the sealing tongue flaps, a sealant 8 being charged in a gap between the side plates.