1. A method for an obstacle alarm, the method comprising: acquiring a captured image in which an image of a visual scene of a periphery of a vehicle has been captured; generating an attention-prioritized captured image on the basis of the captured image, the captured image being the image of the visual scene of a rearward periphery of the vehicle; determining whether or not an object is present in the periphery of the vehicle; determining a movement direction of the object; and causing a frame sign, which has a smaller outer shape than an outline of the attention-prioritized captured image and is to be displayed at sequentially varying positions from an outer edge part of the attention-prioritized captured image toward a center of the attention-prioritized captured image, and for repeatedly performing displaying the frame sign as the frame sign at varying centerward positions, so as to gradually become smaller, where it is determined that the object is moving toward the center of the attention-prioritized captured image, wherein the outer shape of the frame sign is similar to the outline of the attention-prioritized captured image.