1. A similar case search apparatus comprising: a similar case database storing similar case information sets each including: examination identification information identifying an examination for obtaining a medical image; imaging information representing each of imaging methods in the case where a plurality of medical images by the respective imaging methods are obtained in the examination; characteristic information representing a content-based characteristic of at least a region in the medical image; and image interpretation/diagnosis support information for supporting interpretation of a medical image the content-based characteristic of which is similar thereto and/or for supporting diagnosis based on the medical image having the similar content-based characteristic, while relating the imaging information of each of the imaging methods to the examination identification information and relating the characteristic information to the imaging information of each of the imaging methods; imaging information acquisition means for obtaining imaging information representing different imaging methods of a plurality of search target images obtained by the imaging methods in an examination, the imaging information which is obtained from accompanying information added to the respective search target images; and similar case search means for carrying out a search of the similar case database for at least the image interpretation/diagnosis support information in a corresponding portion of the similar case information sets satisfying all of search conditions comprising: a first search condition that the imaging information representing the respective imaging methods of the search target images exists; a second search condition that the imaging information representing the respective imaging methods is related to the examination identification information representing one and the same examination; and a third search condition that the characteristic information related to the imaging information representing each of the imaging methods represents similarity in the content-based characteristic to at least a region in a corresponding one of the search target images by the corresponding imaging method.