This image processing apparatus includes: a planar image acquisition unit configured to acquire a planar image showing a polarization state of a subject, a tomographic image acquisition unit configured to acquire a three-dimensional tomographic image including a plurality of two-dimensional tomographic image of the subject, a display control unit configured to display, on the display unit, an index indicating a position of a tomographic image to be displayed on the display unit among a plurality of two-dimensional tomographic images, by superimposing it on a planar image showing the polarization state, and an instruction unit configured to give an instruction to change a position of the index on a planar image showing the polarization state.
