In a head-up display device, when a preceding vehicle exists between a
pre-movement information conveyor and a vehicle, the pre-movement
information conveyor is moved to another position at which the
pre-movement information conveyor is displayed as a recognizable
post-movement information conveyor. Thus, the pre-movement information
conveyor is removed from a state in which the pre-movement information
conveyor is hidden behind the preceding vehicle, hence, becoming
invisible. As a result, the incompatibility sense felt by the driver of
the vehicle can be reduced and the information conveyor will be less
overlooked.