A raindrop detecting device for detecting a raindrop amount on a windshield of a vehicle and selecting a wiping mode of a wiper based on the detected raindrop amount includes a controller for lowering the wiping mode when the detected raindrop amount is kept to be smaller than a mode-keep threshold while the wiper performs a predetermined number of wiping operations. The controller changes the predetermined number of wiping operations based on at least one of a sensitivity data of a user of the vehicle and a rainfall block data relative to the vehicle.