A spindle-bearing protecting device for protecting a bearing that supports a spindle so as to be rotatable, includes: a rotating part positioned further to an outer side in an axial direction than the bearing, and having a rotor blade configured to rotate along with the spindle; a supply part configured to supply coolant or lubricant between the rotor blade and the bearing; a detection unit configured to detect abnormality of the bearing; and a control unit configured to control a supply of the coolant or the lubricant by the supply part and a revolution speed of the spindle, in a case where the detection unit detects abnormality of the bearing.