PURPOSE: To enable the number of revolutions of a drive shaft to be selected in at least two stages by providing a transmission mechanism to transmit a power from a motor to a drive shaft and a control part to control the number of revolutions of the motor.

CONSTITUTION: During production of bread dough, a capacitor motor 20 repeats forward running and reversing through output of a gate signal synchronized with a 50/60Hz source signal alternately through output ports O3 and O4 from a microcomputer 34. In this case, since approximately 100% power is fed to the capacitor motor 20, the motor performs full running, and is decelerated by means of a pulley 22, and a blade 17 is rotated approximately at 300rpm. During high frequency heating, since a power fed to the capacitor motor 20 is reduced to a low value, a 2-period cycle in which after energization is effected only in a half period, no energization is made for a specified period is repeated. A power fed to the motor is finely adjustable by varying the number or periods in which no energization is made. By selecting the number of frequencies at which no energization is made, feedback control is performed so that a food placing table 33 is rotated approximately at 6rpm.