1. A posture estimating apparatus comprising: an inputting unit configured to input a range image including a multi-joint object; a deriving unit configured to derive at least one joint position candidate for each of a plurality of joint positions of the object, from the range image input by the inputting unit; a storing unit configured to store information including a positional relation between a joint in a multi-joint object model corresponding to the object and other joint; and an estimating unit configured to estimate a posture of the object on the basis of the information including the positional relation and the derived joint position candidate.