An imaging apparatus for diagnosis comprising: a transmitting and receiving unit configured to carry out signal transmission and reception while moving continuously in an axial direction in a tubular tissue, and to obtain a reflected signal; a signal processing unit configured to construct a plurality of cross-sectional images in a direction perpendicular to the axis of the tubular tissue based on the reflected signal; and a display unit comprises a first display area configured to display a longitudinal- sectional image in an axial direction of the tubular tissue constructed by using data used for the respective cross-sectional images, and a second display area configured to display the cross-sectional image corresponding to an arbitrary position in an axial direction in the longitudinal-sectional image displayed in the first display area; characterized in that the signal processing unit is configured to divide the second display area into at least two individual areas (611, 612) in case of accepting an instruction to the effect that a predetermined operation is executed with respect to the first display area, and display at least two indicators (621, 622) for indicating the position of the axial direction in the longitudinal-sectional image in the first display area in case of accepting an instruction to the effect that the predetermined operation is executed; and the display unit displays cross-sectional images corresponding to the axial direction position which is indicated by the at least two indicators (621, 622), in respective individual areas of the second display area, in a case in which the second display area is divided into at least two individual areas (611,612), wherein the signal processing unit is further configured such that in a case in which the positions indicated by two indicators (621, 622) within the indicators are determined, the distance between the two indicators (621, 622) is calculated, and the calculated distance is displayed in the first display area, and a distance display line connecting the two indicators is displayed between the two indicators (621, 622), and the two indicators (621, 622) are movable in parallel in the axial direction while maintaining the distance therebetween in a case in which the distance display line is dragged. a transmitting and receiving unit configured to carry out signal transmission and reception while moving continuously in an axial direction in a tubular tissue, and to obtain a reflected signal; a signal processing unit configured to construct a plurality of cross-sectional images in a direction perpendicular to the axis of the tubular tissue based on the reflected signal; and a display unit comprises a first display area configured to display a longitudinal- sectional image in an axial direction of the tubular tissue constructed by using data used for the respective cross-sectional images, and a second display area configured to display the cross-sectional image corresponding to an arbitrary position in an axial direction in the longitudinal-sectional image displayed in the first display area; characterized in that the signal processing unit is configured to divide the second display area into at least two individual areas (611, 612) in case of accepting an instruction to the effect that a predetermined operation is executed with respect to the first display area, and display at least two indicators (621, 622) for indicating the position of the axial direction in the longitudinal-sectional image in the first display area in case of accepting an instruction to the effect that the predetermined operation is executed; and the display unit displays cross-sectional images corresponding to the axial direction position which is indicated by the at least two indicators (621, 622), in respective individual areas of the second display area, in a case in which the second display area is divided into at least two individual areas (611,612), wherein the signal processing unit is further configured such that in a case in which the positions indicated by two indicators (621, 622) within the indicators are determined, the distance between the two indicators (621, 622) is calculated, and the calculated distance is displayed in the first display area, and a distance display line connecting the two indicators is displayed between the two indicators (621, 622), and the two indicators (621, 622) are movable in parallel in the axial direction while maintaining the distance therebetween in a case in which the distance display line is dragged.