To reduce the electric power consumption of a servomotor for rotating and driving a driving shaft of a cycle sewing machine, to prevent the heat generation of a motor, and to miniaturize a power circuit.

This cycle sewing machine is provided with a control device comprising a motor driving circuit 32 for driving a sewing machine motor 10 for rotating the driving shaft, an encoder 34 for detecting speed of the motor 10 to output a speed detection signal, a CPU 36 for outputting a speed command signal of each of patterns corresponding to acceleration, constant sped, and deceleration, a comparator 38 for outputting a speed deviation signal ΔV based on the speed detection signal and each speed command signal, and an amplifier 40 for outputting a current command signal K.ΔV obtained by multiplying the deviation signal ΔV by a specified speed gain K to the motor driving circuit 32 such that a detected speed is matched with a command speed. When the speed command corresponding to the constant speed is outputted from the CPU 36, a switching signal is outputted to the amplifier 40, and the speed gain is made smaller than that outputted when the speed command corresponding to the acceleration/deceleration is outputted.