A periphery monitoring device includes: an acquisition section acquiring a steering angle of a vehicle; an image acquisition section acquiring a captured image from an image capturing section that captures an image of a periphery of the vehicle; a detection section acquiring detection information of an object around the vehicle; and a control section causing a display section to display a synthesized image including a vehicle image showing the vehicle and a periphery image showing the periphery of the vehicle based on the captured image. When the object is detected on a course of the vehicle traveling at the steering angle by a predetermined distance, the control section causes a virtual vehicle image to be displayed in the synthesized image to be superimposed on a course to the object with a position of the vehicle as a reference.