A sewing machine driven by a motor which is adapted to be energized by an alternate current power supply and is phase controlled by means of thyristors. In a normal operating mode the conduction phase of the thyristors is made variable as a function of the extent of the depression of a foot controlled pedal, whereas in a low constant speed mode the thyristors are made conductive at a predetermined phase. The motor is coupled to a main shaft which is provided with a magnet located at a predetermined position, while a bracket arm is provided with a reed switch located at a predetermined position, such that if and when the foot controlled pedal is released, the reed switch is actuated to trigger the thyristors for reverse braking of the motor as a function of the counter electromotive force of the motor. Preferably, a timer is provided for interrupting the power supply after the lapse of a predetermined time period after the foot controlled pedal is released.