A double-jet film cooling structure for a wall of a gas turbine engine comprising: an injection port, formed on a wall surface of the wall facing a passage of a high-temperature gas, to inject a cooling medium (CL, CL3 - CL7) toward a downstream side of the passage; a main passage in the form of a straight round hole formed in the wall to supply the cooling medium (CL, CL3 - CL7) to the injection port; a pair of branch passages (4, 5) formed in the wall, branching from a branch point on the main passage, each in the form of a straight round hole having the injection port as an outlet; and communication passages (6, 7) formed in the wall that allow the main passage to communicate with respective branch passages (4, 5) and have the injection port as an outlet, wherein injection directions of cooling medium components respectively injected from the pair of branch passages (4, 5) are inclined with respect to a flow direction of the high-temperature gas so as to form respective swirl flows (V1, V2) of the cooling medium components oriented in directions to push each other against the wall surface, the main passage and the branch passages (4, 5) have transverse cross-sections having the same constant inner diameters, each of the communication passages (6, 7) has an envelope surface (16, 17) obtained by continuously arranging straight round holes each of which passes the branch point and has a transverse cross-section having the constant inner diameter, respective transverse injection angles (β) of the injection directions from the pair of branch passages (4,5) with respect to the flow direction of the high-temperature gas, along the wall surface, are set to be oriented in opposite directions from each other with respect to the flow direction, and a main longitudinal angle (α1) formed between an axial direction of the main passage and the wall surface is set to be greater than a respective branch longitudinal angle (α2) formed between an axial direction of each branch passage (4, 5) and the wall surface. an injection port, formed on a wall surface of the wall facing a passage of a high-temperature gas, to inject a cooling medium (CL, CL3 - CL7) toward a downstream side of the passage; a main passage in the form of a straight round hole formed in the wall to supply the cooling medium (CL, CL3 - CL7) to the injection port; a pair of branch passages (4, 5) formed in the wall, branching from a branch point on the main passage, each in the form of a straight round hole having the injection port as an outlet; and communication passages (6, 7) formed in the wall that allow the main passage to communicate with respective branch passages (4, 5) and have the injection port as an outlet, wherein injection directions of cooling medium components respectively injected from the pair of branch passages (4, 5) are inclined with respect to a flow direction of the high-temperature gas so as to form respective swirl flows (V1, V2) of the cooling medium components oriented in directions to push each other against the wall surface, the main passage and the branch passages (4, 5) have transverse cross-sections having the same constant inner diameters, each of the communication passages (6, 7) has an envelope surface (16, 17) obtained by continuously arranging straight round holes each of which passes the branch point and has a transverse cross-section having the constant inner diameter, respective transverse injection angles (β) of the injection directions from the pair of branch passages (4,5) with respect to the flow direction of the high-temperature gas, along the wall surface, are set to be oriented in opposite directions from each other with respect to the flow direction, and a main longitudinal angle (α1) formed between an axial direction of the main passage and the wall surface is set to be greater than a respective branch longitudinal angle (α2) formed between an axial direction of each branch passage (4, 5) and the wall surface.