To provide a grinder, reducing the power consumption related to a grinding wheel bearing such as racing power of a bearing part, bearing oil cooling power and bearing pump power to thereby reduce the quantity of energy consumed from the start to the end of grinding a work.

The power consumption of the bearing part or the quantity of energy consumed from the start to the end of grinding a work is set to a predetermined quantity, and the outside diameter of the bearing part is determined to apply predetermined rigidity at a grinding point according to the preset value.