A bicycle display device is configured to show an image on a display that is appropriate to a bicycle component, which is communicable with the bicycle display device. The bicycle display device is configured to be mounted on a bicycle. The bicycle display device includes a communication unit, a display and an electronic controller. The communication unit is communicably connected to a bicycle component that is mounted on the bicycle and configured to be actuated in multiple actuation modes. The display is configured to show an image related to the actuation modes of the bicycle component, which is one of different types of bicycle components. The electronic controller changes the image shown on the display in accordance with the type of the bicycle component communicably connected to the communication unit.