1. An image processing apparatus comprising: an acquisition unit configured to acquire position information of a contact region between an object and a holding member based on an image obtained by imaging the object in a held state in which the object is held by the holding member; and an estimation unit configured to estimate a three-dimensional shape of the object in the held state based on the position information of the contact region, wherein the image includes a two-dimensional image, wherein the acquisition unit is configured to acquire two-dimensional position information of the contact region in the two-dimensional image, wherein the estimation unit is configured to estimate the three-dimensional shape such that two-dimensional position information of a region obtained by projecting a calculated contact region contacting the holding member onto the two-dimensional image corresponds to the two-dimensional position information of the contact region acquired by the acquisition unit, and wherein one or more of the acquisition unit or the estimation unit are implemented by a processor and a memory.