1. A computer-readable recording medium that stores therein a computer program for analyzing a panorama image that is created by processing a series of picture frames, the computer program making a computer execute: extracting a partial image to constitute a part of the panorama image, from one picture frame among the picture frames; calculating optical flows of the one picture frame; associating each of the optical flows with each pixel in the partial image; and calculating a distance to a subject appearing in the partial image based on the associated optical flows.