Process for manufacturing a structural component (1, 1', 1'', 1′′′, 1ʺʺ) in composite material comprising a skin and at least one stiffening stringer (3, 3', 3ʺ, 3′′′, 3ʺʺ) applied rigidly and integrally to a face of said skin; said process comprising the following steps: a) arranging on a tool (12, 12', 12ʺ, 12ʺʺ) a plurality of first layers (4; 4a', 4b'; 4ʺ; 4′′′; 4aʺʺ, 4bʺʺ, 4cʺʺ) of uncured or pre-cured composite material forming said stringer (3, 3', 3ʺ, 3′′′, 3ʺʺ), wherein said stringer (3, 3′, 3ʺ, 3′′′, 3ʺʺ) presents a longitudinal axis and has a raised portion (7, 7', 7ʺ, 7′′′, 7ʺʺ) protruding from at least one flange extending parallel to said longitudinal axis and along a lying surface, which is flat or is a surface of revolution; b) arranging on said tool (12, 12', 12ʺ, 12ʺʺ) a plurality of second layers of uncured or pre-cured composite material forming said skin; c) making a face of said skin, parallel to said lying surface, and said flange of said stringer (3, 3′, 3ʺ, 3′′′, 3ʺʺ) adhere to each other; d) applying predetermined temperature and pressure on the assembly thus formed so as to compact said layers together, possibly curing the uncured material and rigidly joining said skin to said stringer (3, 3', 3ʺ, 3′′′, 3ʺʺ); e) performing a cutting operation on the free end side edge/s of said flange in a slanted direction with respect to said lying surface and to the layers (4; 4a', 4b'; 4ʺ; 4′′′; 4aʺʺ, 4bʺʺ) forming the flange itself and in such a way that the cut layers (4, 4a', 4b', 4'', 4′′′, 4aʺʺ, 4bʺʺ) of said flange have, in the subsequent phase c), an extension along said lying surface, increasing towards the skin itself; and f) covering at least said end side edge/s of said flange with a coating of composite material so as to seal outwards the layers (4; 4a', 4b'; 4ʺ; 4′′′; 4aʺʺ, 4bʺʺ) cut in step e) and forming said flange; said coating of composite material defining, at the end of said process, a constituent or integral part of said structural component (1, 1', 1ʺ, 1′′′, 1ʺʺ); characterized by further comprising, after step e), the step of g) laminating at least a further layer of composite material forming said stringer (3, 3', 3", 3′′′, 3ʺʺ) that is applied on the side of the stringer (3, 3', 3", 3′′′, 3ʺʺ) itself opposite to the one to be applied to said face of said skin; said further layer having one or two lateral end flaps protruding with respect to the cut side edge/s of said flange; said step f) being carried out by folding said lateral end flap/s of said further layer on the respective said cut side edge/s of said flange to cover it/them and seal it/them outwards and to define said coating of composite material. a) arranging on a tool (12, 12', 12ʺ, 12ʺʺ) a plurality of first layers (4; 4a', 4b'; 4ʺ; 4′′′; 4aʺʺ, 4bʺʺ, 4cʺʺ) of uncured or pre-cured composite material forming said stringer (3, 3', 3ʺ, 3′′′, 3ʺʺ), wherein said stringer (3, 3′, 3ʺ, 3′′′, 3ʺʺ) presents a longitudinal axis and has a raised portion (7, 7', 7ʺ, 7′′′, 7ʺʺ) protruding from at least one flange extending parallel to said longitudinal axis and along a lying surface, which is flat or is a surface of revolution; b) arranging on said tool (12, 12', 12ʺ, 12ʺʺ) a plurality of second layers of uncured or pre-cured composite material forming said skin; c) making a face of said skin, parallel to said lying surface, and said flange of said stringer (3, 3′, 3ʺ, 3′′′, 3ʺʺ) adhere to each other; d) applying predetermined temperature and pressure on the assembly thus formed so as to compact said layers together, possibly curing the uncured material and rigidly joining said skin to said stringer (3, 3', 3ʺ, 3′′′, 3ʺʺ); e) performing a cutting operation on the free end side edge/s of said flange in a slanted direction with respect to said lying surface and to the layers (4; 4a', 4b'; 4ʺ; 4′′′; 4aʺʺ, 4bʺʺ) forming the flange itself and in such a way that the cut layers (4, 4a', 4b', 4'', 4′′′, 4aʺʺ, 4bʺʺ) of said flange have, in the subsequent phase c), an extension along said lying surface, increasing towards the skin itself; and f) covering at least said end side edge/s of said flange with a coating of composite material so as to seal outwards the layers (4; 4a', 4b'; 4ʺ; 4′′′; 4aʺʺ, 4bʺʺ) cut in step e) and forming said flange; said coating of composite material defining, at the end of said process, a constituent or integral part of said structural component (1, 1', 1ʺ, 1′′′, 1ʺʺ);