Heat seal paper and packaging bag

Problem to be solved: To provide heat seal paper excellent in impact resistance and processability. [Solution] the heat seal paper has at least one heat seal layer on at least one surface of a paper base material. The heat seal paper has a structure in which a longitudinal tensile energy absorption amount measured according to JIS P 8113:2006 is X1a, a lateral tensile energy absorption amount measured according to JIS P 8113:2006 is Y1a, a longitudinal tension energy absorption amount measured according to JIS P 8113:2006 is Y2a, Wherein the synergistic average of X1a and Y1a is 120 J/m 2 or more, the ratio of X1a to Y1a (X1a/Y1a) is 0.5 or more and 2.0 or less, and the synergistic average of X2a and Y2a is 2.0 J/g or more, when the specific tensile energy absorption amount in the lateral direction measured in accordance with JIS P 8113:2006 is Y2a....