In step S1, image data obtained by imaging is input to an image input unit (1). In step S2, the diagnosis result obtained by a doctor using the image data obtained by imaging is input as diagnosis information to a diagnosis information input unit (2). In step S3, a keyword table (7) is searched for a keyword input to the diagnosis information input unit (2) or a diagnosis information analyzing unit (3). In step S4, a parameter determining unit (5) selects an initial value parameter used in an image search unit (4) from an initial value table (8) on the basis of the input keyword. In steps S5 and S6, the image search unit (4) determines the optimization degree of the selected parameter by applying the parameter to the input image on the basis of the area or connectivity of a morbid region, and also extracts a morbid region by using a general computer aided diagnosis technique.