A safety device for shielding a medical needle, includes a hand grip element; a cannula held at the hand grip element; a base with laterally protruding, flat wings, the base having a guide opening which is spaced apart from the underside and in which the cannula is guided; and a connecting structure which connects the handle element with the base and includes two elongated sections connected in a row with one another by at least one joint and the connecting structure is connected at one end by at least one joint with the hand grip element and, at the other end, by at least one joint with the base, the elongated section of the connecting structure, which is connected with the base has a wall element which protrudes transversely at its base end, and the connecting structure can be unfolded from a first state into a second extended state.