The invention relates to a device (10) for safe access to a confined space, comprising: a rectilinear support strut (12), two arms (14, 16) each fixed rigidly to an end (12a) of the strut, at right angles thereto and in opposite directions. A first arm (14) comprises at least one anchoring element (18), the second arm (16) being provided with at least two pulleys (20, 22) whose axis of rotation is at right angles to the plane defined by the strut and the arms. The anchoring element (18) and the two pulleys (20, 22) are arranged so as to allow the passage of a cordage of the anchoring element to the pulleys without interfering with the strut and the first and second arms. The strut (12) has at least one fixing member intended to cooperate with an opening (84) of the confined space in order to ensure the fixing thereof.