Provided is a connection structure for connecting a connection member having an attaching portion attachable to an endoscope, to a wire protective sheath into which an endoscope operation wire is configured to be partially inserted for protection. The connection structure includes: a through-hole disposed in the connection member, the wire protective sheath being insertable into the through-hole; and at least one swaging portion located at a different position from that of the attaching portion to partially constitute a peripheral wall of the through-hole. While the wire protective sheath is inserted into the through-hole, the at least one swaging portion is pressed to partially deform the through-hole, thereby connecting the connection member to the wire protective sheath.