Provided is an estimation apparatus for estimating a position or an attitude of a second portion with respect to a first portion in an apparatus including the first portion, the second portion, a movable mechanism, a magnetic sensor, and a magnet section. The estimation apparatus includes an estimation unit which performs, based on a combination of measured values and reference information, an estimation of the position or the attitude of the second portion with respect to the first portion. The reference information includes first reference information and second reference information. The estimation apparatus includes a selection unit which selects, according to a degree of coincidence between the combination of the measured values and each of the first reference information and the second reference information, the first reference information or the second reference information which has a higher degree of coincidence as the reference information for the estimation.