The door handle device includes: a contact sensing unit including a guide groove and a contact sensing electrode, the guide groove configured to guide a water droplet falling on a door, the contact sensing electrode disposed in the guide groove and configured to sense a contact with the door; a locking unit configured to execute unlocking and locking of a door; and a control unit configured to instruct to the locking unit to keep locking the door if determining that the water droplet is in contact with the door, on the basis of a sensing result by the contact sensing electrode. There are provided: a contact sensing device; a door handle device and a control method for such a door handle device; and an electronic key system, for preventing a misoperation due to a water droplet adhering to a door handle of vehicles, which has an electrostatic locking mechanism.