Antenna device

An antenna device (10) includes an antenna (21) that performs wireless communication with an electronic key (K). A substrate (40) is connected to the antenna (21). A housing (13A) includes the antenna (21) and the substrate (40). A cover (30) is coupled to the housing (13A) to cover the substrate (40), which is exposed from the housing (13A). The cover (30) includes a part formed from a transparent material and facing at least part of the substrate (40).