An intake apparatus of an internal combustion engine, comprising: an intake apparatus main body including a plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) being connected to cylinders (111,112, 113, 114) of the internal combustion engine, respectively, the internal combustion engine having the plurality of cylinders (111, 112, 113, 114) and an external gas passage (30; 230) distributing an external gas to each of the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223); wherein the intake apparatus main body is formed such that a plurality of pieces being formed so as to be divided from one another is joined with one another, and the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) are formed so as to be curved, the external gas passage (30; 230) is disposed at an inner circumferential side of the plurality of curved intake pipes (21, 22, 23, 24; 221, 222, 223), the external gas passage (30; 230) being provided at a joint surface of the plurality of pieces constituting an inner circumferential part of the plurality of curved intake pipes (21, 22, 23, 24; 221, 222, 223), the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) is formed so as to be curved in a direction in which the external gas passage is disposed so as to be contained in the inner circumferential side of the intake pipes (21, 22, 23, 24; 221, 222, 223) until an upstream end of the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) faces an intermediate portion of the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223), the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) is re-curved in the direction in which the external gas passage is disposed so as to be contained in the inner circumferential side of the intake pipes (21, 22, 23, 24; 221, 222, 223) after linearly extending by a predetermined distance from the intermediate portion and a downstream end is connected to the cylinder head of the internal combustion engine, the external gas passage (30; 230) is disposed at an area where the upstream end and the intermediate portion of the plurality of curved intake pipes (21, 22, 23, 24; 221, 222, 223) face with each other, the intake apparatus of an internal combustion engine further comprises a surge tank connected to the upstream end of the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223), and the plurality of pieces includes a first piece, a second piece, and a third piece, wherein the surge tank is formed by joining the first piece and the second piece at a first joint surface and by joining the first piece and the third piece at a second joint surface, and the external gas passage (30; 230) is formed by joining the first piece and the second piece at the first joint surface. an intake apparatus main body including a plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) being connected to cylinders (111,112, 113, 114) of the internal combustion engine, respectively, the internal combustion engine having the plurality of cylinders (111, 112, 113, 114) and an external gas passage (30; 230) distributing an external gas to each of the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223); wherein the intake apparatus main body is formed such that a plurality of pieces being formed so as to be divided from one another is joined with one another, and the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) are formed so as to be curved, the external gas passage (30; 230) is disposed at an inner circumferential side of the plurality of curved intake pipes (21, 22, 23, 24; 221, 222, 223), the external gas passage (30; 230) being provided at a joint surface of the plurality of pieces constituting an inner circumferential part of the plurality of curved intake pipes (21, 22, 23, 24; 221, 222, 223), the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) is formed so as to be curved in a direction in which the external gas passage is disposed so as to be contained in the inner circumferential side of the intake pipes (21, 22, 23, 24; 221, 222, 223) until an upstream end of the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) faces an intermediate portion of the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223), the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223) is re-curved in the direction in which the external gas passage is disposed so as to be contained in the inner circumferential side of the intake pipes (21, 22, 23, 24; 221, 222, 223) after linearly extending by a predetermined distance from the intermediate portion and a downstream end is connected to the cylinder head of the internal combustion engine, the external gas passage (30; 230) is disposed at an area where the upstream end and the intermediate portion of the plurality of curved intake pipes (21, 22, 23, 24; 221, 222, 223) face with each other, the intake apparatus of an internal combustion engine further comprises a surge tank connected to the upstream end of the plurality of intake pipes (21, 22, 23, 24; 221, 222, 223), and the plurality of pieces includes a first piece, a second piece, and a third piece, wherein the surge tank is formed by joining the first piece and the second piece at a first joint surface and by joining the first piece and the third piece at a second joint surface, and the external gas passage (30; 230) is formed by joining the first piece and the second piece at the first joint surface.