An insertion device for applying an infusion set to the body of a patient, wherein the device has two actuation members which have to be actuated simultaneously to trigger an insertion movement by which a cannula of the infusion set is introduced into the body and wherein, in some embodiments, one of the actuation members is a securing slide including a contact face to be placed on the body of the patient, the securing slide being actuated by the insertion device being pressed, via the contact face, against the body of the patient.