1. A target analysis apparatus having a depth image and an intensity image of a target as an input, the target analysis apparatus comprising: a body detection unit to detect a body of the target from the intensity image of the target; a foreground segmentation unit to calculate an intensity threshold value in accordance with intensity values from the detected body, to transform the intensity image into a binary image using the intensity threshold value, and to mask the depth image of the target using the binary image as a mask to thereby obtain a masked depth image; and an active portion detection unit to detect an active portion of the body of the target from the masked depth image.