An image diagnostic device of the present invention includes image display means (16) for displaying a diagnostic image and input means (18) for setting position a plurality of specifying marks ON the displayed diagnostic image and distance measuring means (19) for measuring a distance among the position specification marks which have been set ON the diagnostic image. The image diagnostic device further includes position specification mark supporting means (20) for generating operation support information for setting another position specification mark in accordance with one position specification mark set by the input means (18). The image display means (16) displays the generated operation support information while correlating it to the diagnosis image.
