A pose estimation apparatus for estimating a pose of a first imager of a stereo camera having a first and second imager whose imaging timings are not synchronous with each other, comprising: said first imager that generates a first standard image captured at a first time and a second standard image captured at a second time; said second imager that generates a first reference image associated with the first time and a second reference image associated with the second time; and an estimator that estimates, based on the first standard image, the second standard image, the first reference image and the second reference image, (a) a pose of the first imager at the first time, with a pose of the first imager at the second time being regarded as a standard and (b) a positional shift of a position of the second imager when capturing the first reference image from an estimated ideal position of the second imager at the first time, wherein the estimated ideal position of the second imager at the first time is calculated by shifting the position of the first imager at the first time in accordance with a positional relationship between the first imager and the second imager, wherein the estimator searches for corresponding feature points in the first standard image, the second standard image, the first reference image and the second reference image, restores positions of the feature points based on the second standard image and the second reference image, and estimates (a) and (b) such that an error between re-projected points obtained by projecting restored positions of the feature points on the first imager and the second imager at the first time and the feature points included in the first standard image and the first reference image is minimized. said first imager that generates a first standard image captured at a first time and a second standard image captured at a second time; said second imager that generates a first reference image associated with the first time and a second reference image associated with the second time; and an estimator that estimates, based on the first standard image, the second standard image, the first reference image and the second reference image, (a) a pose of the first imager at the first time, with a pose of the first imager at the second time being regarded as a standard and (b) a positional shift of a position of the second imager when capturing the first reference image from an estimated ideal position of the second imager at the first time, wherein the estimated ideal position of the second imager at the first time is calculated by shifting the position of the first imager at the first time in accordance with a positional relationship between the first imager and the second imager, wherein the estimator searches for corresponding feature points in the first standard image, the second standard image, the first reference image and the second reference image, restores positions of the feature points based on the second standard image and the second reference image, and estimates (a) and (b) such that an error between re-projected points obtained by projecting restored positions of the feature points on the first imager and the second imager at the first time and the feature points included in the first standard image and the first reference image is minimized.