An antenna device that can suitably be provided on the exterior of a vehicle is provided with low cost. An antenna case includes a top cover and a bottom plate joined with each other. The top cover stores an antenna module that receives a signal and a packing member provided at the joining part between the top cover and the bottom plate to keep the antenna case tightly sealed. The antenna case has a notch positioned at the joining part through which a signal line is externally extended, and the packing member integrally forms a base part that covers the entire surface of the antenna module and a gasket part that covers the outer periphery of the signal line connected to the antenna module in the position of the notch.