To calculate a distance between one's own vehicle and an obstacle without depending on whether or not the obstacle is already known in a vehicle periphery monitoring device.

This vehicle periphery monitoring device 1 is composed of front side cameras 10a and 10b, an image processing means 20, a vehicle speed sensor 30, an ultrasonic wave sensor 40, an announcing processing means 50, an announcing indicator 60, an announcing buzzer 70, and an on-vehicle monitor 80. A side obstacle distance calculating means 22 is composed of a characteristic area extracting part 22a for extracting a characteristic area from image information, a characteristic area luminance acquiring part 22b for acquiring the luminance distribution of the characteristic area, a retrieving area extracting part 22c for acquiring a retrieving area, a retrieving area luminance acquiring part 22d for acquiring the luminance distribution of the retrieving area, a moving distance calculating part 22e for calculating a moving distance on an obstacle image from coincident retrieval of the two luminance distributions, and a distance calculating part 22f for calculating a distance up to the obstacle by the moving distance on the obstacle image, a camera moving distance, and a camera parameter. The announcing processing means 50 indicates proper announcing output on the basis of a calculated distance.