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, wherein the active portion of the body includes at least one part of the body having a relatively large motion, wherein a non-active portion of the body of the target includes a human head and torso, and the active portion includes human arms and legs.