1. A breast cancer pathological image diagnosis support device for supporting a diagnosis based on pathological images by using an HE-stained image and an IHC image as said pathological images of breast cancer, the device comprising: a computer processor; and a memory which stores a program implementing: a matching unit executed by the computer processor, which calculates a matching position of said HE-stained image and said IHC image; a specifying unit executed by the computer processor, which specifies, based on information of a tumor area specified in said HE-stained image and information of said matching position calculated by said matching unit, an area in the IHC image corresponding to the tumor area specified in the HE-stained image and specifies the specified area as a tumor area in the IHC image; and a calculating unit executed by the computer processor, which calculates a staining positive cell content rate in said tumor area based on information of the tumor area in said IHC image specified by said specifying unit, wherein said calculating unit converts image data of said tumor area of said IHC image into an HSV color space, calculates a threshold value by discrimination analysis of a value of H (hue) in the HSV color space of the image data, discriminates a brown area and a blue area in the tumor area of the IHC image on the basis of the calculated threshold value, extracts, in the tumor area of the IHC image, nucleus in the brown area to count the number of nuclei to obtain the number of staining positive cell nuclei, and extracts nucleus in the blue area to count the number of nuclei to obtain the number of staining negative cell nuclei, and calculates the staining positive cell content rate in said tumor area of the IHC image.