A fixing device for fixating a blade segment of a rotor blade of a wind turbine to a mould in which the blade segment is manufactured, wherein the blade segment has a fixating extension, the fixing device comprising: - a first portion comprising a first abutment structure to selectively exert a clamping force on the fixating extension of the blade segment; and - a second portion for fixating the fixing device to the mould, characterized in that the fixing device comprises at least one of each of a clamping force structure and a retaining structure; the clamping force structure comprising - an aperture and a recess with a second abutment structure within the aperture, the aperture and the recess being arranged in one of the first and second portions (11, 12); - a clamping drive having a cylinder portion with a threaded structure and a threaded abutment structure encircling the cylinder portion and engaging the threaded structure; and - a third abutment structure arranged in the other one of the first and second portions (12, 11); wherein the aperture is adapted to receive the clamping drive cylinder portion such that the cylinder portion protrudes the aperture along its cylinder axis; wherein the second abutment structure is adapted to engage and exert a force on the threaded abutment structure in a direction parallel to the cylinder axis, and wherein the third abutment structure is adapted to receive a force from the clamping drive cylinder portion in a direction towards the first abutment structure to exert the clamping force; and the retaining structure comprising - a lateral opening arranged in one of the first and second portions (11, 12), and - a retaining web arranged on the other one of the first and second portions (12, 11), the retaining web being adapted for insertion into the lateral opening along an insertion direction, wherein the lateral opening is adapted to lock a movement of the retaining web in a direction perpendicular to the insertion direction and to the direction of the clamping force, characterized in that said lateral opening extends from the aperture and allows the cylinder portion shifting into the aperture in a direction perpendicular to the cylinder axis. - a first portion comprising a first abutment structure to selectively exert a clamping force on the fixating extension of the blade segment; and - a second portion for fixating the fixing device to the mould, - an aperture and a recess with a second abutment structure within the aperture, the aperture and the recess being arranged in one of the first and second portions (11, 12); - a clamping drive having a cylinder portion with a threaded structure and a threaded abutment structure encircling the cylinder portion and engaging the threaded structure; and - a third abutment structure arranged in the other one of the first and second portions (12, 11); - a lateral opening arranged in one of the first and second portions (11, 12), and - a retaining web arranged on the other one of the first and second portions (12, 11), the retaining web being adapted for insertion into the lateral opening along an insertion direction, wherein the lateral opening is adapted to lock a movement of the retaining web in a direction perpendicular to the insertion direction and to the direction of the clamping force, characterized in that said lateral opening extends from the aperture and allows the cylinder portion shifting into the aperture in a direction perpendicular to the cylinder axis.