A production method of a hair prosthesis comprising following steps: A) predisposing an artificial scalp shaped like a cap and comprising, a relative concave surface, destined to face onto the bald or thinning scalp of a user, and relative to a convex surface, opposite the concave surface; B) predisposing a plurality of hairs; C) inserting each hair of the plurality of hairs by realising a relative hole in the artificial scalp, which extends from a relative first point at the convex surface to a relative second point at the concave surface, causing a first part of each hair to exit from the relative first point; and causing a second part of each hair to exit from the relative second point; D) obtaining, on the convex surface from which the first part of each hair of the plurality of hairs exits, a temporary layer made of a first material, which is soluble in a first solvent, so as to fix, temporarily, the inserted plurality of hairs to the artificial scalp; E) shaving to zero the second part of each hair of the plurality of hairs at the concave surface while the plurality of hairs inserted is temporarily fixed to the convex surface, in such a way that each hair has a relative first end which projects from the convex surface; and a relative second end arranged in the relative hole at the concave surface; F) obtaining, on the concave surface: a first permanent fixing layer solidly constrained to the concave surface; and a plurality of permanent fixing elements, wherein each permanent fixing element of the plurality of permanent fixing elements: originates from the first permanent fixing layer and extends into a relative hole, realised in the insertion step C); and is solidly constrained to the relative hole and to the relative hairs of the plurality of hairs inserted therein, wherein the first permanent fixing layer and the plurality of permanent fixing elements are made of a second material, which is insoluble in the first solvent, to fix together and permanently each hair of the plurality of hairs inserted in the insertion step C); G) optionally, spreading, spraying or extruding onto the first permanent fixing layer a liquid composition comprising a second solvent and a third medical grade material and insoluble in the first solvent and/or a precursor of the third material, solubilised or dispersed in the second solvent, and leaving to evaporate or cause to evaporate the second solvent in order to obtain a second permanent layer which is solidly constrained to and facing the first permanent fixing layer and is made of the third medical grade material; and H) solubilising the temporary layer of the first material by means of the first solvent. A) predisposing an artificial scalp shaped like a cap and comprising, a relative concave surface, destined to face onto the bald or thinning scalp of a user, and relative to a convex surface, opposite the concave surface; B) predisposing a plurality of hairs; C) inserting each hair of the plurality of hairs by realising a relative hole in the artificial scalp, which extends from a relative first point at the convex surface to a relative second point at the concave surface, causing a first part of each hair to exit from the relative first point; and causing a second part of each hair to exit from the relative second point; D) obtaining, on the convex surface from which the first part of each hair of the plurality of hairs exits, a temporary layer made of a first material, which is soluble in a first solvent, so as to fix, temporarily, the inserted plurality of hairs to the artificial scalp; E) shaving to zero the second part of each hair of the plurality of hairs at the concave surface while the plurality of hairs inserted is temporarily fixed to the convex surface, in such a way that each hair has a relative first end which projects from the convex surface; and a relative second end arranged in the relative hole at the concave surface; F) obtaining, on the concave surface: a first permanent fixing layer solidly constrained to the concave surface; and a plurality of permanent fixing elements, wherein each permanent fixing element of the plurality of permanent fixing elements: originates from the first permanent fixing layer and extends into a relative hole, realised in the insertion step C); and is solidly constrained to the relative hole and to the relative hairs of the plurality of hairs inserted therein, wherein the first permanent fixing layer and the plurality of permanent fixing elements are made of a second material, which is insoluble in the first solvent, to fix together and permanently each hair of the plurality of hairs inserted in the insertion step C); G) optionally, spreading, spraying or extruding onto the first permanent fixing layer a liquid composition comprising a second solvent and a third medical grade material and insoluble in the first solvent and/or a precursor of the third material, solubilised or dispersed in the second solvent, and leaving to evaporate or cause to evaporate the second solvent in order to obtain a second permanent layer which is solidly constrained to and facing the first permanent fixing layer and is made of the third medical grade material; and H) solubilising the temporary layer of the first material by means of the first solvent.