1. An image data management apparatus comprising: property information obtaining means for obtaining property information items of an image data set to be managed; security processing method setting means for setting either no security processing or a specific security processing method for each of the items of the property information obtained from the property information obtaining means; security processing means for carrying out the specific security processing method on each of the items of the property information for which the security processing method has been set by the security processing method setting means; attachment decision means for deciding that first ones of the items of the property information are to be attached to the image data set; attachment means for attaching the first ones of the items of the property information decided by the attachment decision means to the image data set; image data storage means for storing the image data set attached with the first ones of the items of the property information by the attachment means; and property information storage means for storing remaining items of the property information not attached to the image data set by the attachment means in a manner to permit access thereof with a corresponding image data set with attached property information, wherein said property information obtaining means includes at least one of image analysis means for obtaining the property information of the image data set by analyzing the image data set and input means for inputting items constituting the property information, the input means being used by a user to input the items of the property information.