A zipper head assembly structure including a zipper head element and a puller is provided. The zipper head includes a zipper head body, a cap body disposed on the zipper head body, and a hook disposed inside the cap body. The cap body includes two curved surfaces opposite to each other. The hook includes a holding part, a hooking part, and a connecting element connecting the holding part and the hooking part. The connecting element includes a protruding block near the holding part. The puller includes a through opening hooked by the locking hook member. The width of the through opening is smaller than the distance between the protruding block and the adjacent curved surface.