A supporter includes a body section having a back-contact section, a first auxiliary band section of which one end is fixed to the top end of a left side of the back-contact section and the other end is fixed to the bottom end of a right side of the back-contact section, a second auxiliary band section forming a pair with the first auxiliary band section, a first ring arranged to slide between the one end and the other end of the first auxiliary band section, a second ring forming a pair with the first ring, a first adjustment band section of which one end is fixed to loops on a right end side of the body section and the other end can be fastened to loops on the right end side of the body section, and a second adjustment band section forming a pair with the first adjustment band section.