A buckle includes a male member having a pair of flexible arms mutually facing each other and disposed extending from a base part, and a female member to connect to the male member by coupling with the pair of arms. The male member has a flexible bridge connecting the pair of arms. The bridge is connected to an opposing face of each of the pair of arms facing the other arm. At the connecting portion where each of the pair of arms and the bridge are connected, the bridge is placed projecting toward the other arm from the opposing face on the arm following a tangential direction to a circle being centered on the base end of the arm and having a distance from the base end to the connecting portion as a radius.