The invention more reliably prevents injury to the heart inside the pericardium when the pericardium is to be perforated and a guide wire inserted. The treatment tool comprises a guide member (2) provided with a distal surface (2a) to be pressed against the outer surface of the pericardium (B), and one or more acicular portions (5) having sharp tips (5a) extending forward at an incline along the circumferential direction at the distal end of a cylindrical body (3a) capable of rotating about an axis (D). The tool further comprises a pericardium-securing member (3) for causing the tips (5a) of the acicular portions (5) to pierce the pericardium (B) due to rotation of the cylindrical body (3a) about the axis (D) to secure the cylindrical body (3a) to the pericardium (B) a perforating member for forming a through-hole for a guide wire in the pericardium (B) to which the pericardium-securing member (3) is secured and tip position limiters (2c, 3c) that cause the position of the tips (5a) in the direction of the axis (D) with respect to the distal surface (2a) of the guide member (2) limited to a position at which the tips (5a) of the pericardium-securing member (3) do not reach the outer surface of the heart (H) while the distal surface (2a) of the guide member (2) is pressed against the outer surface of the pericardium (B).La présente invention porte sur lamélioration de la prévention de lésion cardiaque à lintérieur du péricarde, lorsque le péricarde doit être perforé et quun fil-guide doit être inséré à lintérieur. Loutil de traitement de linvention comprend un élément guide (2), pourvu dune surface distale (2a) devant être comprimée contre la surface externe du péricarde (B), et une ou plusieurs parties aciculaires (5) dotées de pointes acérées (5a) sétendant vers lavant, selon une inclinaison dans la direction circonférentielle, à lextrémité distale dun corps cylindrique (3a) susceptible deffectuer une rotation autour dun axe (D). Ledit outil comprend en outre : un
