In the present invention, in an operation handle 8, a forward/reverse movement switching lever 14 is provided for switching between forward movement and reverse movement. A false operation prevention mechanism 40 that restricts switching to a reverse movement position caused by operation of the forward/reverse movement switching lever 14 is provided on the same side as the operation handle 8. An acceleration lever 15 that adjusts the rotation speed of an engine 3 is provided. The operation of the forward/reverse movement switching lever makes it possible to release the maintenance of the acceleration lever position and to switch between forward movement and reverse movement. In order to reduce operation load and prevent false operation of the reverse operation, an interlocking mechanism 30 that moves the acceleration lever 15 to the low speed side in unison with the reverse movement operation of the forward/reverse movement switching lever 14 is provided between the forward/reverse movement switching lever 14 and the acceleration lever 15. The interlocking mechanism 30 is provided with an interlocking range α in which the operation of the forward/reverse movement switching lever 14 occurs in unison with the operation of the acceleration lever 15 and a non-interlocking range β in which the operation of the forward/reverse movement switching lever 14 causes a forward/reverse movement switching device 28 to operate but the operation of the forward/reverse movement switching lever 14 is not in unison with the acceleration lever 15.Selon la présente invention, dans une poignée d'actionnement (8), un levier de commutation de mouvement vers l'avant/vers l'arrière (14) est utilisé pour commuter entre un mouvement vers l'avant et un mouvement vers l'arrière. Un mécanisme de prévention de fausse manœuvre (40), qui limite la commutation vers une position de mouvement inverse provoquée par le fonctionnement du levier de commutation de mouvement vers l'avant/vers l'arrière (14),
