A sealing apparatus for a secondary battery, adapted to seal a sealing part of a case in which an electrode assembly and an electrolyte are accommodated, the sealing apparatus comprising: a sealing member comprising a first sealing piece and a second sealing piece, adapted to thermally fuse a surface of the sealing part to seal the sealing part, wherein the first sealing piece and the second sealing piece comprise a plurality of thermal fusion parts (211a, 212a), which are disposed from an outer end of a surface of the sealing part toward an inner end that is opposite to the outer end to thermally fuse the surface of the sealing part, and non-thermal fusion parts (211b, 212b), which are disposed between the plurality of thermal fusion parts (211a, 212a), are provided as an opening groove that is opened in a direction of the surface of the sealing part and do not seal the surface of the sealing part, characterized in that the thermal fusion part (211a, 212a) disposed on the inner end of the sealing part has an upward inclined surface (211a-1, 212a-1) that is inclined toward the inner end of the sealing part, and the upward inclined surface gradually decreases pressing force toward the inner end of the sealing part to deform a width of the inner end of the sealing part so that the width gradually increases; the thermal fusion part (211a, 212a) disposed on the outer end of the sealing part has a downward inclined surface (211a-2, 212a-2) that is inclined toward the outer end of the sealing part, and the downward inclined surface gradually increases pressing force toward the outer end of the sealing part to deform a shape of the outer end of the sealing part into a sharp shape; and wherein the non-thermal fusion part of the first sealing piece and the non-thermal fusion part of the second sealing piece are disposed to correspond to each other. a sealing member comprising a first sealing piece and a second sealing piece, adapted to thermally fuse a surface of the sealing part to seal the sealing part, wherein the first sealing piece and the second sealing piece comprise a plurality of thermal fusion parts (211a, 212a), which are disposed from an outer end of a surface of the sealing part toward an inner end that is opposite to the outer end to thermally fuse the surface of the sealing part, and non-thermal fusion parts (211b, 212b), which are disposed between the plurality of thermal fusion parts (211a, 212a), are provided as an opening groove that is opened in a direction of the surface of the sealing part and do not seal the surface of the sealing part, characterized in that the thermal fusion part (211a, 212a) disposed on the inner end of the sealing part has an upward inclined surface (211a-1, 212a-1) that is inclined toward the inner end of the sealing part, and the upward inclined surface gradually decreases pressing force toward the inner end of the sealing part to deform a width of the inner end of the sealing part so that the width gradually increases; the thermal fusion part (211a, 212a) disposed on the outer end of the sealing part has a downward inclined surface (211a-2, 212a-2) that is inclined toward the outer end of the sealing part, and the downward inclined surface gradually increases pressing force toward the outer end of the sealing part to deform a shape of the outer end of the sealing part into a sharp shape; and wherein the non-thermal fusion part of the first sealing piece and the non-thermal fusion part of the second sealing piece are disposed to correspond to each other.