A flange joint connection structure, comprising: a flange joint (1; 100); a pressure pipe, said flange joint (1; 100) comprising: a center hole, for said pressure pipe being inserted into; an insertion-side face, said face being on a side on which the pressure pipe aligned on a centerline is inserted into the center hole; a connection-side face, said face being on a side to which another component is connected; an outer circumferential surface; said surface connecting the insertion-side face and the connection-side face; horizontal holes penetrating parallel to the center hole between the insertion-side face and the connection-side face, in which horizontal bolts are fastened; vertical holes each comprising an inner wall being provided with a screw thread, said pressure pipe comprising: an outer circumferential surface inserted into the center hole of the flange joint (1; 100); recesses arranged in positions corresponding to the vertical holes; the recesses and the vertical holes being respectively arranged on the flange joint (1; 100) and the pressure pipe at intervals of equal angle and shifting positions on the centerline between the insertion-side face and the connection-side face, wherein bolts screwed into the vertical holes of the flange joint (1; 100) from the outer circumferential surface penetrate and are interfitted to the recesses, characterized in that said vertical holes penetrate from the outer circumferential surface to the center hole between the insertion-side face and the connection-side face so as to lie between the horizontal holes. a flange joint (1; 100); a pressure pipe, said flange joint (1; 100) comprising: a center hole, for said pressure pipe being inserted into; an insertion-side face, said face being on a side on which the pressure pipe aligned on a centerline is inserted into the center hole; a connection-side face, said face being on a side to which another component is connected; an outer circumferential surface; said surface connecting the insertion-side face and the connection-side face; horizontal holes penetrating parallel to the center hole between the insertion-side face and the connection-side face, in which horizontal bolts are fastened; vertical holes each comprising an inner wall being provided with a screw thread, said pressure pipe comprising: a center hole, for said pressure pipe being inserted into; an insertion-side face, said face being on a side on which the pressure pipe aligned on a centerline is inserted into the center hole; a connection-side face, said face being on a side to which another component is connected; an outer circumferential surface; said surface connecting the insertion-side face and the connection-side face; horizontal holes penetrating parallel to the center hole between the insertion-side face and the connection-side face, in which horizontal bolts are fastened; vertical holes each comprising an inner wall being provided with a screw thread, said pressure pipe comprising: an outer circumferential surface inserted into the center hole of the flange joint (1; 100); recesses arranged in positions corresponding to the vertical holes; the recesses and the vertical holes being respectively arranged on the flange joint (1; 100) and the pressure pipe at intervals of equal angle and shifting positions on the centerline between the insertion-side face and the connection-side face, wherein bolts screwed into the vertical holes of the flange joint (1; 100) from the outer circumferential surface penetrate and are interfitted to the recesses, characterized in that said vertical holes penetrate from the outer circumferential surface to the center hole between the insertion-side face and the connection-side face so as to lie between the horizontal holes.