1. A deinterlacing method for converting an interlaced image into a progressive image, comprising steps of: performing a filtering process to pixels of at least one of three fields, a deinterlacing target field to be subjected to a deinterlacing process and forward and backward fields of the deinterlacing target field within the interlaced image, thereby generating an interpolation pixel for the deinterlacing target field; measuring a quantity of motion of the deinterlacing target field; and changing characteristics of the filtering on the basis of the quantity of the motion.