A tubular shaft splicing device capable of transmitting torque, comprising: - adjacent first and second end portions (11, 21) of contiguous first and second tubular shaft stretches (10, 20) of a tubular shaft having a longitudinal axis; - at least one splicing plate (30, 40) superimposed to the adjacent first and second end portions (11, 21); and - passing-through locking members (51, 52) inserted in aligned locking holes (13, 14; 23, 24; 33, 34; 43, 44) formed in the first and second end portions (11, 21) and in the at least one splicing plate (30, 40), the passing-through locking members (51, 52) comprising a rectangular or trapezium cross-section; and the locking holes (13, 14; 23, 24; 33, 34; 43, 44) formed in the first and second end portions (11, 21) and in the at least one splicing plate (30, 40) have a conjugated rectangular or trapezium shape, wherein two sides of the rectangular or trapezium shape are parallel to the longitudinal axis; characterized in that the locking holes (13, 14; 23, 24; 33, 34; 43, 44) comprise several pairs of shaft locking holes (13, 14; 23, 24) formed in opposite wall sections of each one of the first and second end portions (11, 21), and several pairs of plate locking holes (33, 34; 43, 44) formed in opposite wall sections of the at least one splicing plate (30, 40), wherein the pairs of plate locking holes (33, 34; 43, 44) are in alignment with the pairs of shaft locking holes (13, 14; 23, 24), wherein the pairs of shaft locking holes (13, 14; 23, 24) and the corresponding pairs of plate locking holes (33, 34; 43, 44) are centred in respective planes perpendicular to the longitudinal axis; the passing-through locking members (51, 52) comprise pairs of first and second passing-through locking members (51, 52) inserted in the pairs of plate locking holes (33, 34; 43, 44) and in the aligned pairs of shaft locking holes (13, 14; 23, 24); the first and second passing-through locking members (51, 52) have protruding end portions protruding from opposite outer surfaces of the at least one splicing plate (30, 40), wherein connection pairs of opposite connection holes (3, 4) perpendicular to the longitudinal axis are formed in the protruding end portions of the first and second passing-through locking members (51, 52), and corresponding fastening screws (6, 7) are installed through the pairs of opposite connection holes (3, 4) and tightened by fastening nuts. - adjacent first and second end portions (11, 21) of contiguous first and second tubular shaft stretches (10, 20) of a tubular shaft having a longitudinal axis; - at least one splicing plate (30, 40) superimposed to the adjacent first and second end portions (11, 21); and - passing-through locking members (51, 52) inserted in aligned locking holes (13, 14; 23, 24; 33, 34; 43, 44) formed in the first and second end portions (11, 21) and in the at least one splicing plate (30, 40), the passing-through locking members (51, 52) comprising a rectangular or trapezium cross-section; and the locking holes (13, 14; 23, 24; 33, 34; 43, 44) formed in the first and second end portions (11, 21) and in the at least one splicing plate (30, 40) have a conjugated rectangular or trapezium shape, wherein two sides of the rectangular or trapezium shape are parallel to the longitudinal axis; characterized in that the locking holes (13, 14; 23, 24; 33, 34; 43, 44) comprise several pairs of shaft locking holes (13, 14; 23, 24) formed in opposite wall sections of each one of the first and second end portions (11, 21), and several pairs of plate locking holes (33, 34; 43, 44) formed in opposite wall sections of the at least one splicing plate (30, 40), wherein the pairs of plate locking holes (33, 34; 43, 44) are in alignment with the pairs of shaft locking holes (13, 14; 23, 24), wherein the pairs of shaft locking holes (13, 14; 23, 24) and the corresponding pairs of plate locking holes (33, 34; 43, 44) are centred in respective planes perpendicular to the longitudinal axis; the passing-through locking members (51, 52) comprise pairs of first and second passing-through locking members (51, 52) inserted in the pairs of plate locking holes (33, 34; 43, 44) and in the aligned pairs of shaft locking holes (13, 14; 23, 24); the first and second passing-through locking members (51, 52) have protruding end portions protruding from opposite outer surfaces of the at least one splicing plate (30, 40), wherein connection pairs of opposite connection holes (3, 4) perpendicular to the longitudinal axis are formed in the protruding end portions of the first and second passing-through locking members (51, 52), and corresponding fastening screws (6, 7) are installed through the pairs of opposite connection holes (3, 4) and tightened by fastening nuts.