The work machine (10) (lawn mower (12)) comprises a main body (14) having a working part (20) for carrying out a predetermined work, and a running motor (36) for generating a rotational driving force for running at least the body (14).Further, the work machine (10) includes a control section (24) for shifting the rotational speed of a traveling operation section (54) for instructing information related to the rotational speed of the running motor (36) and a running motor (36) designated by a traveling operation section (54) based on a variation in the load applied to the work section (20)； .作業機（１０）（芝刈機（１２））は、所定の作業を行う作業部（２０）を有する本体部（１４）と、少なくとも本体部（１４）を走行させる回転駆動力を発生させる走行モータ（３６）と、を備える。また、作業機（１０）は、走行モータ（３６）の回転速度に関わる情報を指示する走行操作部（５４）と、走行操作部（５４）から指示された走行モータ（３６）の回転速度を、作業部（２０）にかかる負荷の変動に基づき変速する制御部（２４）と、を備える。
