A vehicle rear body structure 10 includes a left rear frame 13 that is formed to have a closed section. The left rear frame 13 has a lower member 22 that is formed to have a thickness dimension larger than an upper member 23 thereof. The left rear frame 13 has a first soft zone 24, a second soft zone 25, and a third soft zone 26. The first to third soft zones 24, 25, and 26 are portions with lower strength. The second soft zone 25 is provided in a ring shape throughout the circumference of the left rear frame 13. The first soft zone 24 and the third soft zone 26 are arranged in a lower half part of the left rear frame 13.