An electrode catheter which has: a catheter shaft (10) and a tip electrode (20) having a spherical portion (21) and is provided with an irrigation mechanism wherein a plurality of irrigation openings (112) are arranged at a tip reduced-diameter section (10A) of the shaft (10), a plurality of inclined lumens (111) are formed in the interior of the tip reduced-diameter section (10A), and the formula: D2 = D1 +2 (L2tanalpha-L1tanbeta) applies, where (D1) is the outer diameter of the catheter shaft (10), (D2) is the diameter of the spherical portion (21), (L1) is the distance from the rear end of the tip reduced-diameter section (10A) to the tip edge of the irrigation openings (112), (L2) is the distance from the tip edge of the irrigation openings (112) to a maximum diameter section of the tip electrode (20), (beta) is the angle of incline of the tip reduced-diameter section (10A), and (alpha) is the angle of incline of the inclined lumens (111), the angle of incline (alpha) being 5.0-12.5 DEG (excluding 9.1-9.3 DEG ). According to this electrode catheter, a liquid can be adequately contacted with a tip hemisphere of the tip electrode having the spherical portion.具有:導管管軸(10),及具有球狀部分(21)的前端電極(20);具備灌注機構的電極導管;於管軸(10)之前端縮徑部(10A)配置有複數個灌注用開口(112),於前端縮徑部(10A)之內部形成有複數個傾斜腔(111),導管管軸(10)之外徑設為(D1),球狀部分(21)之直徑設為(D2),自前端縮徑部(10A)之後端至灌注用開口(112)之前端緣部為止之距離設為(L1),自灌注用開口(112)之前端緣部至前端電極(20)之最大徑部為止之距離設為(L2),前端縮徑部(10A)之傾斜角度設為(β),傾斜腔(111)之傾斜角度設為(α)時,成立式:D2≒D1+2(L2.tanα-L1.tanβ)之關係,傾斜角度(α)為5.0~12.5°(除去9.1~9.3°)。依據該電極導管,液體可以充分接觸具有球狀部分的前端電極之前端半球面。100‧‧‧消融導管10‧‧‧導管管軸10A‧‧‧前端縮徑部11‧‧‧腔(液體流路)111‧‧‧傾斜腔112‧‧‧灌注用開口20‧‧‧前端電極21‧‧‧前端膨出部22‧‧‧頸部23‧‧‧圓筒狀部分90‧‧‧溫度感測器95‧‧‧導線21A‧‧‧前端半球面40‧‧‧環狀電極D1‧‧‧導管管軸之外徑D2‧‧‧球狀部分之直徑L1‧‧‧由前端縮徑部之後端至灌注用開口之前端緣部為止的管軸軸方向之距離L2‧‧‧灌注用開口之前端緣部至前端電極之最大徑部為止的管軸軸方向之距離β‧‧‧導管管軸之前端縮徑部的傾斜角度α‧‧‧傾斜腔之傾斜角度EX‧‧‧由區隔傾斜腔的內側之直線被延長而成的外插線(延長線)
