A tailstock transferring apparatus comprising: a ball screw which is rotated by being supplied with driving power from one side; a connecting member which accommodates the other side of the ball screw; and a thrust generating unit which is fastened to the connecting member and provides thrust in a direction toward the other side of the ball screw when the ball screw receives force in one side direction, wherein the thrust generating unit includes: a main housing; a cylinder which is accommodated in the main housing and has one or more fluid accommodating grooves (132aa, 132ab); a piston which is movably accommodated in the cylinder; a first cap which is fixed to the cylinder and seals an outer circumferential surface of the piston; said apparatus being characterised in that: one side of the piston is fastened to the connecting member, and has a fluid flowing groove formed to communicate with the one or more fluid accommodating grooves (132aa, 132ab); the thrust generating unit further includes: a second cap which is fixed to the outer circumferential surface of the piston so as to be spaced apart from the first cap at a predetermined interval; and a spring which is disposed between the first cap and the second cap, and wherein the fluid flowing groove has an orifice formed in a direction toward the one or more fluid accommodating grooves (132aa, 132ab). a ball screw which is rotated by being supplied with driving power from one side; a connecting member which accommodates the other side of the ball screw; and a thrust generating unit which is fastened to the connecting member and provides thrust in a direction toward the other side of the ball screw when the ball screw receives force in one side direction, wherein the thrust generating unit includes: a main housing; a cylinder which is accommodated in the main housing and has one or more fluid accommodating grooves (132aa, 132ab); a piston which is movably accommodated in the cylinder; a first cap which is fixed to the cylinder and seals an outer circumferential surface of the piston; said apparatus being characterised in that: one side of the piston is fastened to the connecting member, and has a fluid flowing groove formed to communicate with the one or more fluid accommodating grooves (132aa, 132ab); the thrust generating unit further includes: a second cap which is fixed to the outer circumferential surface of the piston so as to be spaced apart from the first cap at a predetermined interval; and a spring which is disposed between the first cap and the second cap, and a main housing; a cylinder which is accommodated in the main housing and has one or more fluid accommodating grooves (132aa, 132ab); a piston which is movably accommodated in the cylinder; a first cap which is fixed to the cylinder and seals an outer circumferential surface of the piston; said apparatus being characterised in that: one side of the piston is fastened to the connecting member, and has a fluid flowing groove formed to communicate with the one or more fluid accommodating grooves (132aa, 132ab); the thrust generating unit further includes: a second cap which is fixed to the outer circumferential surface of the piston so as to be spaced apart from the first cap at a predetermined interval; and a spring which is disposed between the first cap and the second cap, and one side of the piston is fastened to the connecting member, and has a fluid flowing groove formed to communicate with the one or more fluid accommodating grooves (132aa, 132ab); the thrust generating unit further includes: a second cap which is fixed to the outer circumferential surface of the piston so as to be spaced apart from the first cap at a predetermined interval; and a spring which is disposed between the first cap and the second cap, and a second cap which is fixed to the outer circumferential surface of the piston so as to be spaced apart from the first cap at a predetermined interval; and a spring which is disposed between the first cap and the second cap, and wherein the fluid flowing groove has an orifice formed in a direction toward the one or more fluid accommodating grooves (132aa, 132ab).