An obstacle alert device that makes explicit to a driver the presence of an obstacle approaching a vehicle, without causing the vicinity of the vehicle to become difficult to see, comprising: a captured image acquisition unit that obtains an image captured of the scene in the vicinity of the vehicle; a target captured image generation unit that generates a target captured image on the basis of the captured image; an object presence determination unit that determines whether or not an object is present in the vicinity of the vehicle; a travel direction determination unit that determines the travel direction of the object; and an explicit image output unit that, when the travel direction determination unit has determined that an object will travel towards the center of the target captured image, displays at sequentially different positions from the outside edge section of the target captured image towards the center thereof, a frame indicator that has a smaller external shape than the outline of the target captured image and is lit for a constant period and then unlit, said explicit image output unit performing this display repeatedly.