TOOL CHANGING DEVICE

PROBLEM TO BE SOLVED: To provide a tool changing device which can change a tool fitted on the spindle of a machine tool with other tool automatically and exactly. SOLUTION: This tool changing device is provided with a first driving mechanism part 44 which drives the rotation of a spline shaft 42 involving a tool changing arm 43 at its front end in a circumferential direction, and a second driving mechanism part which drives the spline shaft 42 so as to advance and retreat in the axial direction, interlocking with the first driving mechanism part 44, whereas the first driving mechanism part 44 is constituted by involving a tubular member 45 fitted on the outer periphery of the spline shaft 42, a plurality of spherical bodies 46 formed at the outer periphery of the tubular member 45, a worm cam 51 which involves a plurality of cam grooves 52 for applying rotational force to the tubular member 45 through the spherical bodies 46, at its outer periphery surface, and a driving shaft 50 which drives the rotation of the worm cam 51.