To provide a metal mold machining device having the high speed rotation of a main spindle and a high rotation accuracy, high static rigidity and dynamic rigidity which can machine efficiently and precisely.

The main spindle 4 of a spindle device 1 for rotating a tool 11 is supported by static pressure magnetic compound bearings 6 to 9. Current detection means 15 to 18 for detecting the exciting current of the static pressure magnetic compound bearings 6 to 9 and a machining state grasping means 19 for grasping the machining state from the current detection value are provided. By providing an outside order response on-off means 20, the static pressure magnetic compound bearings 6 to 9 are supported by only the static pressure gas bearing by the outside order. The measuring means of the housing 5 temperature and a temperature measurement corresponding output means 77 are provided.