A walk-behind self-propelled machine, comprising: a drive motor (30)； a handle (41), provided with two grip portions (411a, 411b) for allowing a user to grip by the left and right hands； a speed adjusting member (42), moving relative to the handle (41) so as to adjust the rotational speed of the drive motor (30), the speed adjusting member (42) being able to be operated by a user when the user grips either of the grip portions by one hand, and the speed adjusting member (42) being provided between the two grip portions (411a, 411b)； and an electromechanical conversion device (43), producing, on the basis of the position change of the speed adjusting member (42) relative to the handle (41), an electrical signal for adjusting the rotational speed of the drive motor (30)； the speed adjusting member (42) moves, relative to the handle (41), between a first position and a second position； the rotational speed of the drive motor (30) at the time when the speed adjusting member (42) is located at the first position is greater than the rotational speed of the drive motor (30) at the time when the speed adjusting member (42) is located at the second position. The speed adjusting member of said walk-behind self-propelled machine can be easily and rapidly operated.L'invention concerne une machine autotractée à pousser, comprenant : un moteur d'entraînement (30) ； une poignée (41), pourvue de deux parties de préhension (411a, 411b) pour permettre à l'utilisateur de la saisir de sa main gauche et de sa main droite ； un élément de réglage de la vitesse (42), mobile par rapport à la poignée (41) pour régler la vitesse de rotation du moteur d'entraînement (30), l'élément de réglage de la vitesse (42) pouvant être actionné par l'utilisateur lorsque celui-ci saisit l'une ou l'autre des parties de préhension d'une main, et l'élément de réglage de la vitesse (42) étant disposé entre les deux parties de préhension (411a, 411b) ； et un dispositif de conversion électromécanique (43), produ
