1. A vehicle, comprising: a sensor configured to detect an object in an area surrounding the vehicle; a head-up display provided on a side of a driver's seat of the vehicle and configured to display the object detected by the sensor by overlaying information at a visual field of a driver of the vehicle; wherein the head-up display is configured to display, in response to the sensor detecting a first object which is a risk to the vehicle, a first mark corresponding to the first object, wherein the head-up display is configured to display the first mark corresponding to the first object and a second mark corresponding to the second object in response to the sensor detecting the first object which is a risk to the vehicle and in response to the sensor detecting a second object equal to or less than a predetermined distance from the first object, the second mark differing from the first mark by at least one from among a color density, a size, and a brightness, and wherein the first mark is a frame displayed in a display area surrounding the first object, the head-up display suppresses the emphasizing degree of the vertical component of the first mark by suppressing an emphasizing degree of a vertical frame portion of the frame.