An antenna main body comprises an antenna element, female connectors provided at a first connector, a female screw section, and an engagement claw inserted into an antenna mount hole H to make engagement with a lower side face of a roof panel R. A fixing member comprises cables, male connectors provided at a second connector, the male connectors being provided to make mechanical engagement with, and electrical connection to, female connectors, and being connected to the cable, and a male screw section helically fitted to a female screw section, thereby tightening the female connectors, the male connectors, and a roof panel R with one another.