PURPOSE: To simultaneously and surely inspect a plurality of tools using simple constitution and at good space efficiency.

CONSTITUTION: A tool breakage detection device has tool heads 22-25 to which a plurality of tools 26, 28 are mounted and a turret head which holds the plurality of tool heads and which allots the tool head 22 to a machining position and a non-machining position by rotation. When the turret head is rotated and the machine head 24 is situated at the uppermost portion of the non- machining position, the tool 28 is held while being oriented vertically upward, and a plurality of detection shafts 36 are provided perpendicular to the tool 28 and a detection holding member 38 is provided for holding the detection shafts 36 in such a manner that the shafts are upwardly movable relative to one another. A moving device 48 for raising the detection shaft holding member 38 is provided and detection units 50, 52 are provided which, when the moving device 48 lowers the detection shaft holding member 38 until the detection shafts 36 abut on the end portion of the tool 28, determine whether all of the detection shafts 36 are in respective predetermined positions.