A location estimating apparatus according to an embodiment includes a degree-of-similarity calculator, a correspondence calculator, and a location calculator. The degree-of-similarity calculator calculates a degree of similarity between the input image and the reference image by an arithmetic operation that varies, in a non-discrete manner, the degree of similarity in accordance with a non-discrete variation of a first parameter. The correspondence calculator calculates correspondence between a pixel of the input image and a pixel of the reference image by an arithmetic operation that varies, in a non-discrete manner, the correspondence in accordance with a non-discrete variation of a second parameter. The location calculator calculates a first location indicating a position and/or an orientation of the first imaging device when the input image is captured by an arithmetic operation that varies, in a non-discrete manner, the first location in accordance with a non-discrete variation of the correspondence.