An attachment device for securing an elongated element on the body of a patient is provided which includes a retaining support for retaining the elongated element, including at least one lower wall and an adhesive strip bearing the retaining support, and intended to be applied on the skin of the patient, the adhesive strip defining at least one region of the attachment device shifted with respect to the lower wall. A region of the attachment device located under the lower wall along an axis for inserting the elongated element into the retaining support is intended to be non-adherent to the skin of the patient. The retaining support comprises a clasping flap able to be maneuvered with respect to the lower wall between an open position and a clasping position of the elongated element. The elongated element is intended to be maintained between the lower wall and the clasping flap.