The present invention provides a needle unit mounted to a medical syringe. The needle unit is provided with: a needle member having a longitudinally extending inner space, the needle member also having a needle hole formed in the side surface of the front end of the needle member, the needle member further having an opening formed in the base end of the needle member, the inner space being in communication with the outside through the needle hole and the opening a base section for supporting the base end of the needle member and providing communication between the syringe and the inner space of the needle member when mounted to the syringe a slide member movable along the outer peripheral surface of the needle member and capable of having a first position where the slide member closes the needle hole and a second position where the slide member uncovers the needle hole at a position close to the base end than the first position a pressing member for pressing the slide member from the second position side to the first position side and a cap removably mounted to the base section so as to cover the needle member.La présente invention concerne une unité daiguille montée sur une seringue médicale. Ladite unité daiguille comprend : un élément aiguille présentant un espace interne sétendant longitudinalement, ledit élément aiguille présentant également un trou daiguille formé dans la surface latérale de lextrémité avant de lélément aiguille, lélément aiguille présentant en outre une ouverture formée dans lextrémité de base de lélément aiguille, lespace interne étant en communication avec lextérieur à travers le trou daiguille et louverture une section de base permettant de supporter lextrémité de base de lélément aiguille et de fournir une communication entre la seringue et lespace interne de lélément aiguille lorsquil est monté sur la seringue un élément coulissant mobile le long de la surface périphérique externe de lélément aiguille et pouvant avoir une première posi
