A shield shell unit includes a shield shell that is attached to an end portion of a shield member for covering a wire, and an attached portion that is attached to the shield shell. The shield shell includes a shell main body, and a fixing portion which projects from the shell main body and is mounted on the attached portion in a direction of intersecting with a direction of attaching the shield shell to the attached portion when the shield shell is attached to the attached portion. The fixing portion and the attached portion have holes which are communicated with each other for passing a screw member therethrough when the fixing portion is mounted on the attached portion.