A Tool for assembling a bone anchoring device is provided, the bone anchoring device includingan anchoring element (2) having a shaft (3) for anchoring in the bone and a head (4),a receiving part formed in one piece, the receiving part having a seat (52) for receiving the head (4) and a channel (54) for receiving a rod (20) to be connected to the anchoring element,a pressure element (6, 601, 602, 603) formed in one piece, the pressure element being movable in the receiving part so as to be able to exert pressure onto the head,wherein the anchoring element is pivotable with respect to the receiving part and can be fixed at an angle by exerting pressure via the pressure element onto the head, and wherein the pressure element (6, 601, 602, 603) comprises a spring element (66, 66) which engages a portion (58, 59) of the receiving part so that the pressure element can be held in a position which allows pivoting of the anchoring elementthe tool including a base portion (91) and a dummy rod portion (93), the dummy rod portion being connectable to the pressure element (6, 601, 602).
