A sheet-like joining member having a ventilation function and used to fix a housing having a vent hole to a support body, the joining member comprising: an air-permeable membrane having a first principal surface and a second principal surface; a first adhesive layer provided on a side of the first principal surface of the air-permeable membrane, the first adhesive layer being adapted to be brought into contact with the housing around the vent hole; an opening formed in the first adhesive layer so that the first principal surface of the air-permeable membrane faces the vent hole of the housing when the first adhesive layer comes into contact with the housing; a second adhesive layer (21, 122) provided on a side of the second principal surface of the air-permeable membrane, the second adhesive layer being adapted to be brought into contact with the support body; and a vent groove (1d, 101d, 201d) formed through the second adhesive layer (22, 122) or between the second adhesive layer and the air-permeable membrane so as to provide an air passage between the housing and the support body to communicate an inside of the housing and an outside of the housing when the housing is fixed to the support body using the joining member, the vent groove including a first portion extending from an outer peripheral edge of the joining member to a region corresponding to the opening and a second portion to which the second principal surface of the air-permeable membrane is exposed in the region corresponding to the opening, wherein the vent groove (1d, 101d, 201d) is formed between the support body and the air-permeable membrane and communicates with the exterior space of the housing when the housing is fixed to the support body using the joining member. an air-permeable membrane having a first principal surface and a second principal surface; a first adhesive layer provided on a side of the first principal surface of the air-permeable membrane, the first adhesive layer being adapted to be brought into contact with the housing around the vent hole; an opening formed in the first adhesive layer so that the first principal surface of the air-permeable membrane faces the vent hole of the housing when the first adhesive layer comes into contact with the housing; a second adhesive layer (21, 122) provided on a side of the second principal surface of the air-permeable membrane, the second adhesive layer being adapted to be brought into contact with the support body; and a vent groove (1d, 101d, 201d) formed through the second adhesive layer (22, 122) or between the second adhesive layer and the air-permeable membrane so as to provide an air passage between the housing and the support body to communicate an inside of the housing and an outside of the housing when the housing is fixed to the support body using the joining member, the vent groove including a first portion extending from an outer peripheral edge of the joining member to a region corresponding to the opening and a second portion to which the second principal surface of the air-permeable membrane is exposed in the region corresponding to the opening, wherein the vent groove (1d, 101d, 201d) is formed between the support body and the air-permeable membrane and communicates with the exterior space of the housing when the housing is fixed to the support body using the joining member.