A motor controller comprises: a motor driver arranged at a housing attached to a machine support; fan motors and arranged in or outside the housing; and a control unit. The motor driver drives motors. The fan motors blow cooling air for cooling the interior of the housing. The CPU includes a machining mode selection unit allowing selection of at least either a first machining mode of machining a machining target finely or a second machining mode of machining the machining target more roughly than in the first machining mode. If the first machining mode is selected, the machining mode selection unit exerts control to change the rotation numbers of the fan motors and so as to reduce vibration to be transmitted from the housing to the support column.