TOOL CHANGING DEVICE

PROBLEM TO BE SOLVED: To improve the operatability in the change of a tool in a MDI mode by comprising a means for determining whether an error judging means is to be operated or not. SOLUTION: Whether the error check is to be set or not is judged (S41). When the error check is to be set (S41: YES), whether a spindle is positioned on an origin in the rotating direction or not is judged (S42). When the spindle is positioned on the origin in the rotating direction (S42: YES), a tool pot takes an advancing attitude, a finger is opened (S44: YES), a tool changing motor is operated and an arm turning motion is executed (S46). When the spindle is not positioned on the origin in the rotating direction (S42: NO), the tool pot does not take the advancing attitude (S43: NO), or a finger sensor is off (S44: NO), the error display is executed on a liquid crystal display board (S46). On the other hand, when the error check is not executed (S41), the arm turning motion is executed regardless of the rotating position of the spindle, the attitude of the tool pot and the opening and closing of the finger (S46).