1. An obstacle alarm device, comprising: a captured image acquisition unit for acquiring a captured image in which an image of a visual scene of a periphery of a vehicle has been captured; an attention-prioritized captured image generation unit for generating an attention-prioritized captured image on the basis of the captured image; an object presence determination unit for determining whether or not an object is present in a periphery of the vehicle; a movement direction determination unit for determining a movement direction of the object; and a clear indication image output unit for causing a frame sign, which has a smaller outer shape than an outline of the attention-prioritized captured image and is turned on for a fixed duration of time and thereafter turned off, to be displayed at sequentially varying positions from an outer edge part of the attention-prioritized captured image toward a center thereof, and for repeatedly performing such displaying, in a case where the movement direction determination unit has determined that the object is moving toward the center of the attention-prioritized captured image.