A method for manufacturing a hoisting rope (2,2') of a hoisting apparatus, such as an elevator, which rope (2,2') comprises one or more composite members as load bearing members of the rope (2,2'), the method comprising: forming an elongated composite member preferably by pultrusion, or providing an elongated composite member and surface treatment of the elongated composite member by plasma treatment rising temperature of said elongated composite member, or providing an elongated composite member and applying of heated coating (c) on the elongated composite member such as by extrusion coating; characterised in that the method comprises inspecting quality and/or condition of said elongated composite member, which is a load bearing member of a hoisting rope (2,2') of a hoisting apparatus, such as an elevator, or a precursor of such a load bearing member, by: changing the temperature of said elongated composite member by cooling by aid of a cooling device said elongated composite member via a flank (1a,1b) thereof, wherein in said cooling heat accumulated in said elongated composite member during said forming, said surface treatment or said applying of heated coating (c)of said elongated composite member or a rope (2,2') comprising said elongated composite member, is removed from said elongated composite member; scanning said elongated composite member from a lateral side thereof with a thermal imaging device after said changing of the temperature; and creating thermographic images of said elongated composite member. forming an elongated composite member preferably by pultrusion, or providing an elongated composite member and surface treatment of the elongated composite member by plasma treatment rising temperature of said elongated composite member, or providing an elongated composite member and applying of heated coating (c) on the elongated composite member such as by extrusion coating; characterised in that the method comprises inspecting quality and/or condition of said elongated composite member, which is a load bearing member of a hoisting rope (2,2') of a hoisting apparatus, such as an elevator, or a precursor of such a load bearing member, by: changing the temperature of said elongated composite member by cooling by aid of a cooling device said elongated composite member via a flank (1a,1b) thereof, wherein in said cooling heat accumulated in said elongated composite member during said forming, said surface treatment or said applying of heated coating (c)of said elongated composite member or a rope (2,2') comprising said elongated composite member, is removed from said elongated composite member; scanning said elongated composite member from a lateral side thereof with a thermal imaging device after said changing of the temperature; and creating thermographic images of said elongated composite member. changing the temperature of said elongated composite member by cooling by aid of a cooling device said elongated composite member via a flank (1a,1b) thereof, wherein in said cooling heat accumulated in said elongated composite member during said forming, said surface treatment or said applying of heated coating (c)of said elongated composite member or a rope (2,2') comprising said elongated composite member, is removed from said elongated composite member; scanning said elongated composite member from a lateral side thereof with a thermal imaging device after said changing of the temperature; and creating thermographic images of said elongated composite member.