A shield unit includes: a braid having a contact portion arranged in contact with a cylinder of a shield shell; a holder inserted in the cylinder and attached to the cylinder in contact with the contact portion, the holder attached to the cylinder electrically connecting the shield shell to the braid; and a rotation unit provided between the cylinder and the holder, the rotation unit being configured to make the holder rotate in a circumferential direction of the cylinder and make the cylinder and the contact portion slide relatively to each other until completion of attaching the holder to the cylinder.