Lawn mower utilizing a work device having a plurality of blades for performing lawn mowing work. A power device is configured to transmit rotational power to each of the plurality of blades, and be capable of optionally changing the rotation number of the rotational power transmitted to each of the plurality of blades. A blade speed detection unit is configured to detect respective speeds of the plurality of blades to a ground. A control device is configured to perform energy-saving control of increasing and decreasing the rotation number of the rotational power transmitted to each of the plurality of blades in accordance with increase and reduction in the detected speed of each of the plurality of blades.