This application relates to an absolute position detection device and detection method of a rotating body. In one aspect, the device includes first row magnets coupled to a rotating body to rotate together and having n pole pairs, and second row magnets coupled to the rotating body to rotate together and having (n+1) pole pairs. The device also includes a first Hall sensor installed adjacent to the first row magnets and configured to detect a change in magnetism according to rotation of the first row magnets. The device further includes a second Hall sensor installed adjacent to the second row magnets and configured to detect a change in magnetism according to rotation of the second row magnets. The device further includes a controller configured to measure an absolute position of the rotating body using signals output from the first and second Hall sensors.