An automatic tool changing device capable of cleaning a contact surface of a spindle, which is to be in contact with a tool holder, with a simple structure. The device includes a turret having a plurality of grippers on its outer circumference and holding the tool holder by means of the grippers. At the time of tool change, the grippers grip and pull out the tool holder fixed to the spindle. Rotation of the spindle causes the turret to rotate through a spindle gear, a turret gear, and a decelerating device, to thereby select a tool. At this moment, a coolant is spouted from a nozzle portion of a manifold toward a spindle taper hole in which the tool holder is interfitted and washes the taper hole. Due to the rotation of the spindle, the coolant is spouted onto the whole circumference of the taper hole, and the surface to be in contact with the tool holder is surely washed. Therefore, it is possible to perform the cleaning with a simple structure in which the nozzle portion is arranged near the spindle without machining the spindle and the tool holder.