The purpose of the present invention is to enable highly precise detection of the position of a movable part even in a case where a plurality of coils are used. For this purpose, an optical unit according to the present invention is characterized by including: a holding unit that holds a group of lenses and that is movable relative to a predetermined fixed unit along the direction of an optical axis of the group of lenses a first magnet that is magnetically polarized in a direction crossing the optical axis and that is provided on one of the fixed unit and the holding unit a plurality of coils that are provided on the other one of the fixed unit and the holding unit, where the first magnet is not provided, and with which, in a case where a current is made to flow therethrough, the current is subjected to a force in the direction of the optical axis, exerted by a magnetic field generated by the first magnet a second magnet that is provided on one of the fixed unit and the holding unit and a magnetic sensor that is provided on the other one of the fixed unit and the holding unit, where the second magnet is not provided, that is disposed at a position where magnetic fields associated with at least two of the plurality of coils can be oriented so as to cancel out each other within a movable range of the holding unit, and that detects a magnetic field generated by the second magnet.Lobjet de la présente invention est de permettre une détection extrêmement précise de la position dune partie mobile même dans un cas où lon utilise une pluralité de bobines. À cet effet, une unité optique selon la présente invention est caractérisée en ce quelle comprend : une unité de maintien qui maintient un groupe de lentilles et qui est mobile par rapport à une unité fixe prédéfinie le long de la direction dun axe optique du groupe de lentilles un premier aimant qui est polarisé magnétiquement dans une direction croisant laxe optique et qui est prévu sur lune parmi lunité fixe ou de lun
