A control unit (41) of a PC (40) acquire three-dimensional OCT data obtained by irradiating measurement light on a two-dimensional measurement region extending in a direction intersecting an optical axis of the measurement light. The control unit (41) sets a line pattern, from among a plurality of types of line pattern, with respect to the two-dimensional measurement region for which the three-dimensional OCT data is obtained. At least one of an arrangement, a number, or a shape of one or more lines is different for the plurality of types of line pattern. The control unit (41) extracts from the three-dimensional OCT data, a two-dimensional tomographic image of a cross section intersecting each of the one or more lines of the set line pattern.
