A condensate trap apparatus comprising: an inlet, through which condensate is introduced; a storage space, in which the condensate introduced from the inlet is stored; a discharge part including an outlet configured to discharge the stored condensate from the storage space; and a buoyant body including a closed part formed to be convex toward a vertically lower side such that the buoyant body is seated on the discharge part to close the outlet, and a columnar support part extending vertically upwards from the closed part, characterized in that the discharge part further includes: an annular discharge packing surrounding the outlet, extending from an edge of the outlet to be inclined toward a radial outside of the outlet and a vertically upper side such that an outer surface of the buoyant body contacts the discharge packing when the buoyant body is seated on the discharge part to close the outlet, wherein the discharge packing has a dual structure including: an annular first contact part disposed on an outermost side with respect to a radial direction of the outlet and contacting the closed part; and an annular second contact part located to be spaced apart from the first contact part inwards, and contacting the closed part. an inlet, through which condensate is introduced; a storage space, in which the condensate introduced from the inlet is stored; a discharge part including an outlet configured to discharge the stored condensate from the storage space; and a buoyant body including a closed part formed to be convex toward a vertically lower side such that the buoyant body is seated on the discharge part to close the outlet, and a columnar support part extending vertically upwards from the closed part, characterized in that the discharge part further includes: an annular discharge packing surrounding the outlet, extending from an edge of the outlet to be inclined toward a radial outside of the outlet and a vertically upper side such that an outer surface of the buoyant body contacts the discharge packing when the buoyant body is seated on the discharge part to close the outlet, wherein the discharge packing has a dual structure including: an annular first contact part disposed on an outermost side with respect to a radial direction of the outlet and contacting the closed part; and an annular second contact part located to be spaced apart from the first contact part inwards, and contacting the closed part. an annular discharge packing surrounding the outlet, extending from an edge of the outlet to be inclined toward a radial outside of the outlet and a vertically upper side such that an outer surface of the buoyant body contacts the discharge packing when the buoyant body is seated on the discharge part to close the outlet, wherein the discharge packing has a dual structure including: an annular first contact part disposed on an outermost side with respect to a radial direction of the outlet and contacting the closed part; and an annular second contact part located to be spaced apart from the first contact part inwards, and contacting the closed part. an annular first contact part disposed on an outermost side with respect to a radial direction of the outlet and contacting the closed part; and an annular second contact part located to be spaced apart from the first contact part inwards, and contacting the closed part.