To realize the safe turning of a traveling vehicle by lowering travel speed in response to operation for turning a steering wheel when the travelling vehicle travels forward or rearward.

A turning movement block 71 mounted with a main shift lever 13 is turningly moved around an X axis 72. A universal joint part 83 of the tip of a turning movement yoke 76 mounted turningly movable around a Y axis 74 on the block 71 is connected to a universal joint part 84 on the Y axis with a second connection lever 85, and that at the position of the tip of an intermediate arm 79 connecting to a traveling hydraulic drive means operation arm part 78 through a first connection lever 81. The yoke 76 is biased by an energizing spring 86 toward the main shift lever 13. The yoke 76 is also connected to a connecting rod 91 through a universal joint 90 and a subordinate arm 89. The axial movement of a connecting rod 91 in response to the operation of a steering wheel forcibly rotates the yoke 76 in a predetermined direction and causes the operating arm 78 to rotate toward a low speed position.