A self-locating device that captures omni-directional camera images and determines its position and posture from the sensed images is disclosed. Omni-directional predicted images of a robot in a supposed moved position from an initial position are generated from omni-directional camera images that can be acquired when the robot is arranged in the initial position, and these predicted images and omni-directional images newly acquired when the robot has actually moved are matched with each other to detect the robot position and posture (direction).