A work management system comprising: a generator attached to a structure body that is provided to a transmission case of a working machine, configured to be driven by power transmitted from a PTO shaft, and configured to transmit power to a working device provided in the working machine; an information obtaining portion configured to obtain operation information representing operation of the working device that is activated by the power from the generator; a work management portion configured to manage working of the working device based on the operation information obtained by the information obtaining portion; and a controller portion configured to control the working device based on the operation information obtained by the information obtaining portion; and a motor configured to be driven by the power from the generator, wherein the working device has a rotor to be turned by power from the motor to spread a spread substance, and wherein the controller portion controls a rotating speed of the rotor based on the operation information; characterized in that the work management system comprises: a posture detector device configured to detect a posture of the working device; and a posture adjuster mechanism configured to adjust the posture of the working device based on the posture detected by the posture detector device, wherein the information obtaining portion obtains, as the operation information, posture information relating to the posture of the working device detected by the posture detector device, and wherein the controller portion controls the rotating speed of the rotor based on the posture information obtained by the information obtaining portion. a generator attached to a structure body that is provided to a transmission case of a working machine, configured to be driven by power transmitted from a PTO shaft, and configured to transmit power to a working device provided in the working machine; an information obtaining portion configured to obtain operation information representing operation of the working device that is activated by the power from the generator; a work management portion configured to manage working of the working device based on the operation information obtained by the information obtaining portion; and a controller portion configured to control the working device based on the operation information obtained by the information obtaining portion; and a motor configured to be driven by the power from the generator, wherein the working device has a rotor to be turned by power from the motor to spread a spread substance, and wherein the controller portion controls a rotating speed of the rotor based on the operation information; a posture detector device configured to detect a posture of the working device; and a posture adjuster mechanism configured to adjust the posture of the working device based on the posture detected by the posture detector device, wherein the information obtaining portion obtains, as the operation information, posture information relating to the posture of the working device detected by the posture detector device, and wherein the controller portion controls the rotating speed of the rotor based on the posture information obtained by the information obtaining portion.